Natraj Jdbc

8/17/2019 Natraj Jdbc

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JDBC

a)When it is given to begin the execution.

b)In the process of creating first object for the class.

c)When Class.forName()is called.

Q:- How can we develop java application without main method?

Ans:-

public class DemoApp1

{

static

{

int a=10;

System.out.println(“square of a =”+a*a);

System.exit(0);

}

}

The above code runs in all java versions up to jdk1.6 and in the

initial release of jdk1.7 but not in other version.

API: Application Programming InterfaceHere the word interface is no way related to java interface. It is

used

Having English meaning based/platform;


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APIs are base for developers to develop software applications.

Every language technology and framework gives different API.

In c language API mean set of function which is in the form of

header files.

C++ API means set of functions, classes which comes in the

form of header files.

In java API means classes, interfaces, enums, annotations

which come in form of packages.

There are 3 types of API.

(i) Built-in APIs (given by language/technology/framework)

(ii) User-Defined APIs (given by programmer)

(iii) Third party APIs (given by other than above two)

Popular Java APIs(built in api)

Utility api(java.util and its sub package)

Jdbc api(java.sql, javax.sql and its sub packges)

JD C : =>

Persistence : =>

Saving data for long time and manage data for

long time is called persistence.

The process of saving and managing data for long time is

called persistence.


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The data stored in variables, objects of application allocates

memory in different part of RAM only during the application

execution. This data, memory vanished once the application is

completed because RAM is temporary memory. In order to

overcome this problem we should write application data to

secondary memory like hard disk to persistence.

Terminologies:-

(1) Persistence store

(2)

Persistence data

(3) Persistence logic

(4) Persistence Technology

CRUD/CURD/SCUD

o C-Create(insert)

o

R- Read (select)o U-Update(modify)

o D- Delete

Terminologies:-

The place where data will be saved

and managed is called persistence store

Persistence Store:-

The data of persistence store is called

persistence data.

Persistence Operation:-


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The insert, update, delete and select

operations performed on persistence data is called persistence

operations. These are also called CURD/CRUD/SCUD

operations.

The logic that is used to perform persistence operation is called

persistence logic.

Eg:- IO Steam code, JDBC code hibernate code.

The technology that can be used to develop persistence logic is

called persistence technologies.

Eg:- JDBC, Hibernate (Framework), spring jdbc(framework)

Every application contains some logic like presentation,

business, service and persistence logic and etc.

The logic that provides user-interface to end user to view

result to supply inputs is called presentation logic.

The logic that generates result is called business logic/service

logic.

The logic that persist data is called persistence logic.

Sample Application:-

R ead student details like no, name, marks (3 subjects)

presentation logic.

Calculate total average Service logic.

Total=m1+m2+m3;

Avg=(m1+m2+m3)/3;


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Generating ranks for students service logic.

Display Result Presentation logic.

Save result, inputs to Db table persistence logic

I/O Stream

Java Application Files

Serialization & Deserialization

Java Application jdbc(sql queries) DataBase

SoftWare(RDBMS)

(oracle, Sybase, mysql -------

--)

Serialization =>

Process of capturing object data and writing that datato file is called serialization.

Deserialization :=>

Reading data form file and constructing object having

that data is called deserialization.

Limitations with files as persistence stores:-

No Security.

Cannot maintain huge amount of data.

No constraints can be applied.

No sql support.


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We cannot define relationship.

Update and delete operation are very complex.

Merging and comparison of data is very complex.

To overcome these problems use database software as persistence

store.

The Advantages are:-

Security

Sql support

Allows to apply constraints, allow to define relationship.

Merging and comparison of data is very easy and etc.

Conclusion:-

Use files as persistence store in small scale application

Use database software as persistence store in large scaleapplication.

Eg: – Banking application, Insurance application etc.

To get interaction between operating system and external devices

of computer like printer we need support of external device of

computer like printer we need device driver.

\


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We need jdbc diver as bridge between java application and

database software. It converts java calls to database calls and vice

versa.

Non java application use odbc driver to interact with database

software.

We cannot use ODBC driver directly in our java applications.


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Some jdbc driver internally uses odbc driver support while

interacting with database software. Some other JDBC driver

directly interacts with database software.

We can get jdbc driver from three vendors :-

(a) Sun Microsystem (oracle corporation)

(b) Database Vendor (Recommended)

(c) Third party vendors.

We can get odbc driver from three vendors.

(a)

Xopen

(b) Database vendors (recommended)

(c) Third party vendors.

Jdbc 4.x Api packages.

java.sql, java.sql packages (core packages)

Javax.sql.RowSet, javax.sql.rowset.Serilizable,javax.sql.Rowset.api(advanced packages)


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Continue

2015-03-12


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What is the difference between language and technology?

Programming language:-

These are raw material directly installable

software as raw material having basic features of application

development.

Programming language define syntax (Rule), Symantec (structure)

of programming.

Language is base for creating technology, framework, operating

system and database software etc.

Eg – c, c++, java etc.

Technologies:-

These are software specification

having set of rules and guideline to develop software by using

programming language.

Technology is not installable but technology based software

installable.

Working with these software is nothing but working with

technologies.

Jdbc is technology software specification that gives set of rules

and guidelines to develop Jdbc driver using java language. Jdbc is

not installable. Working with jdbc driver is nothing but working

with JDBC .


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There are two types of technology are:-

(1) Open technology:-

These technologies are rules and guidelines

open for multiple vendor companies to develop the software.

Eg:- All jsp, jee technology (jdbc, jndi, servlet etc)

(2) Proprietary technology:-

The vendor that has given these technologies are only

allowed to develop software based on the technologies.

Eg:-All Microsoft Technology.


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Since all jdbc driver given by different vendor companies are

coming based on the common rules and guidelines of jdbc

technology so we can work with all these jdbc driver in a

common way in the application development.

The interfaces of jdbc API packages represent rules of jdbc

technology and the classes of jdbc API packages represent

guidelines of jdbc technology.

Every jdbc driver is a collection of classes implementing various

interfaces of jdbc Api packages and all these classes contain logic

to interact with sertain database software and to send and execute

sql queries in database software.

Q:- What is jdbc?

Ans :- It is an open java technology given by sun microsystem having

set of rules and guidelines to develop jdbc driver for differencedatabase software.

ODBC :->

It is an open technology given by Xopen has set of rules

and guidelines to develop odbc driver for different database software.

Every technology gives one API. This API will be used by vendor

companies as rules and guidelines to develop software‖s .The same

API will be used by programmers to work with technology based

software in the application development.


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Eg. The API of jdbc technology will be used by vendor companies

as rules and guidelines to develop jdbc drivers and the same api

will be used by programmer in application development to

activate jdbc drivers and to develop jdbc persistence logic.

java.sql.Driver (interface)

^

| extends

sun.jdbc.odbc.jdbcOdbcDriverInterfacd (Interface)

^

| implements

sum.jdbc.odbc

Even though multiple class in every jdbc driver we just know

diver class name in order to activate and use these jdbc driver in

our java application.

Every Jdbc driver is identified with its driver class. It is the class

supplied by vendor company of jdbc driver implementing

java.sql.Driver Interface directly or indirectly.

Upto jdk1.7 we get one built in jdbc driver given by sum

Microsoft in rt.jar file. This jdbc driver is identified with its driver

class .


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sum.jdbc.odbc.JdbcOdbcDriver

(package )|(class name)

The above jdbc driver class implements java.sql.DriverInterface

directly as shown below:-

Java.sql.Driver(interface)

^

| extends

Sun.jdbc.odbc.JdbcOdbcDriverInterface(interface)

^

| Implements

Sum.jdbc.odbc.JdbcOdbcDriver(class)

Along with window operating system installation we get multiple

ODBC driver every odbc driver is identified with its DSN.

There are three types of DSNs available thses are: -

(1) User Dsn :- specified currently logged in user.

(2) System Dsn : - Spcific to all the window users of a

computer.

(3) File system Dsn :- Sharable in the network.

Procedure to create dsn for Microsoft odbc driver for oracle

Step 1) Make sure that oracle is installed.

Step 2) Add oracle installation related bin directory to path

environment variable (My Computer)


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Step 3) My computer property Advance system settings

environment variablesuser/System variablesvariable name:

path

Value: ;c:\oracle

xe\app\oracle\porduct\10.2.0\server\Bin;ok(3).

Steps (3) create user DSN for micro soft odbc driver for oracle(window

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C:\window\syswow64\odbca32userDsn(tab) addMicrosoft

odbc for oracle/oracle xefinished.

Data source name :oraDsn

Description :[dsn for microsoft odbc driver oracle]

User name: scott

Server :

Server:

This value is optional while working with local oracle. Thisvalue is mandatory while working with centralize network. (Gaither

Dsn String from admin)

Vendor companies can use one of the five mechanism

/architecture/methodology to develop jdbc driver for different Data

Base software based on the rule and guideline of jdbc technology .

They are :--

(1) Type-1 driver (jdbc-odbc bridge driver)

(2) Type-2 driver (Native API /partly java driver)

(3) Type-3 driver (Net protocol/all java driver)


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(4) Type-4 driver (Native protocol/All java driver)

(5) Type-5 driver (not yet confirmed by sum micro system so there

is no technical name)

Partial Architecture of Type-1 jdbc driver:-

This type-1 driver is designed to talk with Data base software

directly. It is designed talk the support of odbc driver to interact

with database software.

We can use one type-1 jdbc driver to talk with multiple database

software by take support of multiple odbc driver.

The jdk supplied build-in jdbc driver is given based on type-1

architecture. Its driver class name issum.jdbc.odbc.JdbcOdbcDriver.

So for only sun Microsoft is giving type-1 diver along with jdk

software installation .(up to jdk 1.7)

Every java application contain one built in service called

Drivermanager service.

Having the capability to manage set of jdbc dirvers.

TO access these services in our application we can use

java.sql.DriverManager class.


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To user JdbcDriver in our java application it must be register with

driver manager service for this we need to keep JdbcDriver class

object in DriverManager service by using register driver

manager.

//Registering jdbc type-1 driver

//creating odbc driver class object

sun.jdbc.odbc.JdbcOdbcDriver obj1=new

sun.jdbc.odbc.JdbcOdbcDriver();

//Register jdbc driver

DriverManager.registerDriver(obj1)

Property of registerDriver(--) method

Public static void registerDriver(java.sql.Driver driver) throws

SQLExceptionThe parameter type of registerDriver(--) method is java.sql.Driver(I), so

we must call that method having implementation class object of that

interface all jdbcdriver class implements java.sql.Driver(I) directly or

indirectly due to this we can call registerDriver(--) having jdbc driver

class object. Notes:-

Sun.jdbc.odbc.JdbcOdbcDriver(c)

Implement java.sql.Driver(I) directly or indirectly.

Three important statements of method parameter types.


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Note: - we cannot create object of interface and abstract classes.

A) If method parameter type is interfaces we call that method having

implementation class object of that interface (refer above)

B) If method parameter is a abstract class. We call that method

having one subclass object of that abstract class as argument.

C) If method parameter type is concrete class, we call that method

having either that class object or one of its subclass object as

argument.

Jdbc application means java application with jdbc code as

persistence logic to manipulate database data.

Jdbc application acts as front end and database software acts as

back end.

What end user see and operate is called front end, what he cannot

see call backend.

Backend(database software) responds based on front end

interaction.

Standard steps to develop jdbc application.

a) Register jdbc driver with Driver Manger Service (Activate jdbc

driver)

b) Established the connection with database software.

c) Create statement object.

d) Send and execute Sql Queries in database software.


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e) Gaither results from database software and process the results.

f) Close connection with database software.

Registering jdbc driver is nothing but placing jdbc driver classobject with driver manager service.

This is mandatory to use jdbc driver in our java applications.

Establishing connection means creating communication channel

between java application and database software.

Jdbc statement object acts as a vehicle between java application

and database software.

To send SQL queries to database software to execute sql queries in

database software and to gather result back to java application

Once operation with database software is completed it is

recommended to close connection with database software.

Q:- Write a jdbc application to establish connection between javaapplication and oracle software using type-1 jdbc driver.

Software Set Up: -

Java any version (jdk 1.7)

Oracle any version (oracle 11g)

Type-1 jdbc (Built in with jdk software dsn create for Microsoft odbc

driver for oracle (“oradsn)

import java.sql.*;


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public class ConnTest

{

public static void main(String args[]) throws Exception

{

//Register odbcDriver(type 1)

//Create jdbc diver class obj

sun.jdbc.odbc.JdbcOdbcDriver obj=new


// register diver

DriverManager.registerDriver(obj);

//Establish the connection with database software

Connection

con=DriverManager.getConnection("jdbc:odbc:oradsn","scott","tiger");

if(con==null){

system.out.println("Connection not established");

}

else

system.out.println("connection is established");

}//main method closed

}//class closed.

27-02-2015


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getConnection method uses given jdbc url , database password details

to use to appropriate jdbc driver, other details while establishing the

connection with database software

Jdbc url syntax

< main protocol >: : sub name

In case of type-1 driver the url is jdbc:odbc:oradsn

Name of dsn

“jdbc” – main protocol

“odbc” – sub protocol

Oradsn – sub name (dsn)

The jdbc driver class name, jdbc url will change based on the

jdbc driver we use and database software we use.

Protocol is set of rules followed by two parties who wants toparticipate in communication.

There are two types of protocol.

(1) Application level protocol

Gives set of rules to get

communication between software services.

Eg: - http, jdbc:odbc

(2) Network level protocol :


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Gives set of rules to get

communication between two physical computer of

network.

Eg: - Tcp/ip.

In the above application

DriverManager.getConnection(“jdbc:odbc:oradsn”,”scott”,”tiger”)

method performs.

(1) Picks up the registered type-1 jdbc driver form DriverManager

service. Based on the protocol “jdbc:odbc” specified in the url.

(2) Type-1 jdk dirver uses odbc driver for oracle based on the dsn

that is specified (oradsn”).

(3) Using both driver (Type-1 odbc driver) the connection

between java application and database software will be created

and the jdbc connection object will be return back to the jdbcconnection object will be returned back to java application

representing that connectivity.

Q:-

Connection

con=DriverManager.getConnction(“jdbc:odbc:oradsn”,”scott”,”tiger”)

When java.sql.Connection is an interface how can we say

DriverManager.getConnection(-, -, -) is returning jdbc

connection object.

Ans:


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Jdbc connection object means it is not object of java.sql.connection .

It is the object of that underlying jdbc driver supplied java class that

implements java.sql.Connection(I). Since this class name changes based

on the jdbc driver we use we never specify this class name in our jdbc

aplications.

In type-1 jdbc driver this name is

“sun.jdbc.odbc.JdbcOdbcConnection” and this class implements java

connection(I) as shown below.

To know class name by object we can use getClass() method.

System.out.println(“connection object name:”+con.getClass());


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Interface reference variable can reference its implementation

class object. DriverManager.getConnection(-, -, -) return the

implementation class object .

Java.sql.Connection(I) and we are referring that object with

java.sql.Connection(i) reference variable (that is “con”).

Properties of getConnection(-, -, -)

public static getConnection(String url,String user,String pwd)

throw SQLException

The return type of DriverManager.getConnection is

java.sql.Connection that means this method returns

implementations class object of java.sql.ConnectionInterface.

Three type of statements on method return types: -

1. If method return type is abstract class then method returns one

subclass object of that class.2. If method return type is interface then method retrun

implementation class object of that interface.

3. If method return type is concrete class then method return

either that concrete class object or one of its subclass objects.

02-28-2015


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Instead of writing two line of code to register jdbc driver with

DriverManager service we can use the following one line of

code for the same purpose.

class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);

class.forName(-) load the given jdbc driver class.

In that purpose the static block of driver class executes.

This static block contains logic to create jdbc driver class

object and logic to create jdbc driver class object and logic to

register that object with DriverManager service by calling

DriverManager.registerDriver() method.

The static block of sun.jdbc.odbc.JdbcOdbeDriver class

looks like this.

Static

{Try

{

JdbcOdbcDriver jdbcodbc=new JdbcOdbcDriver();

DriverManager.registerDriver(jdbcodbcdriver);

}

Catch(Exception)

{

e.printStackTrace();

}


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}

Different ways of reading input from keyboard.

1) Using Scanner Class (jdk 1.5 onbord)

2) Using Command line arguments

3) Using user defined system property

4) Using BufferedReader

5) Using java.io.Console (jdk 1.6)

import java.io.*;

import java.util.*;

public class ReadInput

{

public static void main(String args[]) throws IOException

{Scanner sc =new Scanner(System.in);

System.out.println("Enter Name-1 : ");

String name1=sc.next();

String name2=args[0];

String name3=System.getProperty("myName");

//using stream

BufferedReader br=new BufferedReader(new

InputStreamReader(System.in));

System.out.println("Enter name-4 :");


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String name4=br.readLine();

//Using console

System.out.println("Enter Name-5 : ");

Console cons=System.console();

String name5=cons.readLine();//display value

System.out.println(name1+" "+name2+" "+name3+" "+name4+"

"+name5);

}>javac ReadInput.java

}> java – DmyName=Raja3 ReadInput Raja2

Setting command line argument

Setting System property value

Once specified passing command line argument is mandatory

Once specified passing system property is optional.

Q: - can you explain different way of registering jdbc DriverManagerwith DriverManager service

Approach-1: -


sun.jdbc.odbc.JdbcOdbcDriver(obj);

import java.sql.*;

public class ConnTest

{


{ //Register odbcDriver(type 1)


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//Create jdbc diver class obj


sun.jdbc.odbc.JdbcOdbcDriver(); // register diver

DriverManager.registerDriver(obj); //Establish the conncection with

database software

Connection


if(con==null)

{

System.out.println("Connection not established");

}

else

System.out.println("connection is established");

}//main method closed}//class closed

In process of creating first object to any class jvm load that class

and executes static block of that class.

In the above code same jdbc driver will be register with

DriverManager service.

First time because of static block of jdbc driver class.

Second time because of explicit call given to

DriverManager.registerDriver(-) method.


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Note: - Registering same jdbc driver is a bad practice so the

approach-1 is bad approach.

Approach-2: -

DriverManager registerDriver(new

sun.jdbc.odbc.JdbcOdbcDriver());

Note: - This approach is very much similar to approach -1 so it is

not recommended to use.

DriverManager.registerDriver(new


Connection


import java.sql.*;

public class ConnTest2

{


{

DriverManager.registerDriver(new


Connection


if(con==null)


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{


}

else



}//class closed

Approach-3



import java.sql.*;


{


{



database software

Connection


if(con==null)


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{


}

else


} }

Approach-4

new sun.jdbc.odbc.JdbcOdbcDriver();

Approach-4 is similar to approach-3 so it is not recommended to

use

Note: -

In approach- 3&4 the driver will registered only for one time butexplicitly created object of driver class will be wasted.

new sun.jdbc.odbc.JdbcOdbcDriver(); // register diver

Connection


import java.sql.*;



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{


{

new sun.jdbc.odbc.JdbcOdbcDriver(); // register diver

Connection


if(con==null)

{


}

else


}//main method closed}//class closed

Approach-5

public class ConnTest5 extends sun.jdbc.odbc.JdbcOdbcDriver

{


{


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Connection


In the above code when jvm load contest class it also loads its

super class called Driver class in this process static block driver

class execute and driver will be registered.

The above code is not recommended because it does not let our

application class to extends from other class like from applet,

HTTPservlet

import java.sql.*;

public class ConnTest5 extends sun.jdbc.odbc.JdbcOdbcDriver

{


{

Connectioncon=DriverManager.getConnection("jdbc:odbc:oradsn","scott","tiger");

if(con==null)

{


}

else




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}//class closed

Approach-6

class.forName(“sun.jdbc.odbc.JdbcOdbeDriver) This is a recommended approach because it registered the driver

only for one time and does not create any west object for driver

class

import java.sql.*;


{


{

if(Class.forName("sun.jdbc.odbc.JdbcOdbcDriver")==null)

{


}

else



}//class closed

Approach=7


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public class contest

{

public static void main(String args[]) throws IOException

{

Class.forName(args[0])

Connection con=new

DriverManager.getConnection(“jdbc:odbc:oradsn”,”scott”,”tiger”);

import java.io.*;

import java.sql.*;

class ConnTest7

{


{

Class.forName(args[0]);

Connection


if(con==null)

{


}

else



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}//class closed

Approach-8Public class contest

{

Public static void main(String args[]) throws Exception

{

String driver=System.getProperty(“myDriver”);

Class.forName(driver);

Connection

con=DriverManager.getConnection(“jdbc:odbc:oradsn”,”scott”,”tiger”)

;

}}

This is similar to approach-7 so not recommended to use.

import java.io.*;

import java.sql.*;

class ConnTest8

{


{

String driver=System.getProperty("mydriver");

Class.forName(driver);


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Connection


if(con==null)

{


}

else



}//class closed

>javac ConnTest8.java

>java – Dmydriver=sun.jdbc.odbc.JdbcOdbeDriver ConnTest8

Approach-9

As part of DriverManager class initialization it attempt to load jdbcdriver class that are there in fixed system property so driver will be

registered automatically.

Class contest

{

Public static void main(String args[]) throws IOException

{


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Connection

con=DriverManager.getConnection(“jdbc:odbc:oradsn”,”scott”,”tiger”)

;

}

}

import java.sql.*;


{


{

Connection


if(con==null)

{System.out.println("The conncetion is not establish");

}

else

System.out.println("the conncetion is establish");

}//>javac ConnTest9.java

}//>java – Djdbc.driver=sun.jdbc.odbc.JdbcOdbcDriver ConnTest

Approach-10


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Since type-1 driver is built in driver of jdk there is no need to

registering that driver with driver manager service.

Public class TestConn10

{

Public static void main(String args[]) throws Exception

{

Connection

con=DriverManager.getConncetion(“jdbc:odbc:oradsn”,”scott”,”tiger”)

;

import java.sql.*;


{

public static void main(String args[]) throws Exception{

Connection


if(con==null)

{

System.out.println("The conncetion is not establish");

}

else

System.out.println("the conncetion is establish");


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}

}

Write a jdbc application that use stud

details based on the given start end rang of student no.

Select * from student where sno>=100 and sno


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Connection


//create statement object

Statement st=con.createStatement();

//prepare SQL Queries

//select * from student where sno>100 and sno


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rs.close();

st.close();

con.close();

}

}

Q: - Write a jdbc application to get student details based on the given

city name.

Q: - Write a jdbc app empno, ename, sal, job details of employee based

on the given dept no.

select empno, ename, sal, job from emp where deptno=10;

while processing resultSet use those index for column value in order

they stored in result set obj not in the order they are available in

database

While retrieving value from Resutlset record we can users.getString() method if u don‖t know the data type.

We can call rs.getxxx(--) method to retrieve the value of record

either with cols name of cols index.

Assignment:-1

Write a program that returns students details based on given initial

characters of student Name?

Assignment: -2


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Write a program that returns Employee details based on the

given three designation.

Q: - When java does not support pointer why does it throws

NullPointer exception

When we invoke method on reference variable that holds null

value we will get “NullPointerException”.

Date d=null;

d.getYear();//Throws NullPointerException

-> Here the word “pointer” is no way related to c/c++ pointers. It is

purely used by having “Dictionary meaning” indicating method is on

reference variable that points to null value.

SOLUTION:

Date d=null;

d=new Date();d.getYear(); //Does not throw NullPointerException

import java.sql.*; (implicit pkg import)

import java.sql.DriverManager;

Important java coding standards;

1) Write proper comments.

2) Avoid implicit pkg imports prefer explicit pkg imports


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Q: - Write a jdbc application to get count of emp table record

Select count(*)from emp;

employee name,jobdetails for the emp who is having highest salaryselect ename,empno,job from emp where sal=(select max(sal) from

emp);

If resultSet object contain exactly one record then process the resultSet

using if(rs.next) method.

If ResultSet contain zero or more record then process that

RecordSet by using while(rs.next()) method.

Once we close jdbc connection it automatically closes relevant

statement, ResultSet object.

Prototype of createStatement()

Public Statement createStatement() throws SQLException

Prototype of executeQuery(--)

Public ResultSet executeQuery(String qry) throws

SQLException

To send and execute non-select sql query in database software we

use executerUpdate() method. This method return numeric value

representing number of record that are affected it will return integer.


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Q:- Write a jdbc application to delete student details based on

given student no.

Delete is a non-select sql query so use executeUpdate() method

for sql query execution.

Refer->aap-2 page no — 19,20

There is no necessity of dealing with ResultSet object.

Sql query that is execute through in database s/w through sql

command it is not auto committed.

Sql queries that is executing by coming from jdbc application

execute in data base s/w by enabling auto commit.

Write a jdbc application to update student name, address, based on

given student number.

Update students set sname=‖raja‖,sad=‖Delhi‖ where sno=901;

App-5 page- 22 and 24

2015-03-06

Notepad, notepad++, editplus are editors

Eclipse, MyEclipse, NetBeans and etc,… are IDEs

IDE provides total environment that is required for the

development and integration of the project.

Eclipse:-

Type: IDE for java environment

Vendor: Eclipse or


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Version: 4.4 (Eclipse luna)

Open source (freeware)

To download s/w : ww.ecllipse.org

(as zip file: Extract zip file for installation)

Two flavors of Eclipse

1) JSE flavor (sdk)

2) Jee flavors

www.nataraz.in/software

Q: - Write a jdbc application to insert record into student table while

gathering details from end users?

Procedure to application by eclipse IDE

Step-1) Launch eclipse ide by choosing its workspace( a folder where

all project will be saved) folder.Step-2) Create java project.

File->new->project->Project name (jdbc proj-1)finish

Step- 3 Develop the above jdbc application in com.nt package of src

folder.

a) Create package(Right click on src foldernewpackagecom.nt

b)

Right click on “com.nt” packagenew classname:InsertTest

InsertTest.java

Refer App4 page no:20.

Ctrl+space bar gives main()


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Ctrl+shift+o

Step-4 run the application

Right click in source filerun as java Appuse run as button of the

menu bar.

To change JRE of the java project in eclipse

Right click on project build path libraries table remove existing Jre

Add library JRE System librarynext

Installed jre — add-standard vm next JRE home[c:\porgram files

(x86)\....--> select jdk finish.

xany

toString () method called on exception object just used to called

exception object that is raised.

printStack() method called on object elaborated details that is

raised.When exception is raised in java method the stack memory of the

method will be filled up with exception related messages. TO print

those messages on console monitor we need to use printStackTrace()

method.

From jdk 1.7try with resource is intro where the resource in try will

be close automatically at the end of try without closing them explicitly.

Try(Scanner sc=new Scanner(System.in))

{


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..

}

The “Sc” will be closed automatically at the end of try block.

Using try with Resource for jdbc code

-

Class InserTest

{

psvm()

{

try(

Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”))

{

catch(exception e){


}

try(conncetion con=DM.getConnection(-,,);

Statement st=con.createStatement())

{

Int res=st.executeUpdate(“delete from student where sno=10”);

If(res==0)

Sop(“record not delete”);


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Else

Sop(“record deleted”);

}//main

}//class

2015-03-07

Notepad, notepad++, editplus are editors

Eclipse, MyEclipse, NetBeans and etc,… are IDEs

IDE provides total environment that is required for the

development and integration of the project.

Eclipse:-

Type: IDE for java environment

Vendor: Eclipse or

Version: 4.4 (Eclipse luna)

Open source (freeware)

To download s/w : wwweclipse.org

(as zip file: Extract zip file for installation)

Two flavors of Eclipse

3)

JSE flavor (sdk)

4) Jee flavors

www.nataraz.in/software


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Q: - Write a jdbc application to insert record into student table while

gathering details from end users?

Procedure to application by eclipse IDE

Step-1) Launch eclipse ide by choosing its workspace( a folder where

all project will be saved) folder.

Step-2) Create java project.

File->new->project->Project name (jdbc proj-1)finish

Step- 3 Develop the above jdbc application in com.nt package of src

folder.

c) Create package(Right click on src foldernewpackagecom.nt

d) Right click on “com.nt” packagenew classname:InsertTest

InsertTest.java

Refer App4 page no:20.

Ctrl+space bar

gives main()Ctrl+shift+o

Step-4 run the application

Right click in source filerun as java Appuse run as button of the

menu bar.

To change JRE of the java project in eclipse

Right click on project build path libraries table remove existing Jre Add

library JRE System librarynext

Installed jre — add-standard vm next JRE home[c:\porgram files

(x86)\....--> select jdk finish.


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xany

toString () method called on exception object just used to called

exception object that is raised.

printStack() method called on object elaborated details that is

raised.

When exception is raised in java method the stack memory of the

method will be filled up with exception related messages. TO print

those messages on console monitor we need to use printStackTrace()

method.

From jdk 1.7try with resource is intro where the resource in try will

be close automatically at the end of try without closing them explicitly.

Try(Scanner sc=new Scanner(System.in))

{..

}

The “Sc” will be closed automatically at the end of try block.

Using try with Resource for jdbc code

-

Class InserTest

{

psvm()


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{

try(

Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”))

{

catch(exception e)

{


}

try(conncetion con=DM.getConnection(-,,);

Statement st=con.createStatement())

{

Int res=st.executeUpdate(“delete from student where sno=10”);

If(res==0)

Sop(“record not delete”); Else

Sop(“record deleted”);

}//main

}//class

Can be execute both select and non-select query by using single

method call Yes possible by using execute() method

This method return type is Boolean.

Prototype


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……………….

Public Boolean execute(String qry) throws SQLException

This method returns “true” when it executes “select” SQL Query.

To get ResutlSet of this select SQL Query use getResultSet()

method.

This method returns values that represents number of records

that are affected because of this non-select Query use

getUpdateCount() method

For example application - ref-6 page no 24.

358

Working with execute method is not industry standard because it does

not give sql result directly more ever we need to call method separately

go gather sql query result (like getResultSet(), getUpdateCount)

Conclusion:

Use executeQuery(_) to send and execute select – SQL QUERY

IN database s/w.

Use executeUpdate(-) to send and execute non-select sql

query in database s/w

Jdbc application to create database table in database s/w.

Note: - create table, drop table and alter table are non-select query.

So we should use executeUpdate () to send and execute these method

in sql query database s/w.


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In real scenario ddl query execution does not takes place

through jdbc code only temp table will be created and dropped to

jdbc code

In every company separate db team will maintain to design the

table will be maintain this team will responsible to execute ddl

form sql prompt

Write a ddl application to

Executing ddl query through jdbc application is not industry standard

because the end result of these queries execution is not same in all the

driver more ever db team is responsible to design table for the project.

Jdbc application is not alternate for sql prompt thse are front end

application interacting with database software support end user.

Miscellaneous command like desc cannot beexecuted through jdbc application.

In one jdbc application we can have multiple connection,

statement , ResultSet 0bj using one connection object you can

create one or more statement object

Using one statement object crate one or more ResultSet object

U can use one ResultSet object to send and execute one or more

sql queries. In database s/w.

Q can we develop java application without user defined class?

Possible with enum.


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Every enum is special java class internally.

2015-03-09

Understanding internals of DriverManager.getConnection(-,-,-)_

Connection

con=DriverManager.getConnection(“jdbc:odbc:oradsn”,”scott”,tiger”);

1) Prototype

Public static Connection getConnection(String url,String user,

String pwd);

getConnection(-,-,-) is the static method DriverManager()

getConnection(-,-,-) getRegister jdbc driver class object based

on the given url(protocol & sub name) and calls connect() on

that object.

The connect() of jdbc driver class creates and returns

implementation class object Connection(I) to getConnection(-,-,_) method and getConnection(-,-,-)returns object to our

application.


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Understanding internals of createStatement() method


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Satatement st=con.createStatement();

(a) createStatement() is non-static method declared in

java.sql.Connection(I).

Prototype: -

Public statement createStatement();

(b) createStatement contains implementation in the

implementation class of java.sql.Connection(I) that is

sun.jdbc.odbc.JdbcOdbcConnection(c) in type-1 driver.

(c) createStatement() method definition contains logic to create and

the implementation class object of java.sql.Statement(I) .That is

object of sun.jdbc.odbc.JdbcOdbcStatement(C) in type-1 diver.

Understanding the internals of executeQuery(-) method

ResultSet rs=st.executeQuery(“select U from students”);


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1) executeQuery(-) is non-execute(-)is non-static method declared

in java.sql.Statemnet(i)

Prototype:

public ResultSet executeQuery(String qry) throws SQLException2) executeQuery(-) is implemented in jdbc driver supplied java class

that implements java.sql.Statement(I). In type-1 driver that class

name is

“sun.jdbc.odbc.JdbcOdbcStatement”.

3) executeQuery(-) internally calls getResutlSet() method.

4)

This getResutlSet() contains logic to crate and return the

implementation class object “java.sql. ResultSet(I).


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2015-03-10

There are 5 mechanisms/architectures to develop jdbc drivers based on

the rules and guide lines of jdbc technology

a) Type-1 driver (Jdbc odbc bridge driver)

b) Type-2 driver (Native API /Partly java driver)

c)

Type-3 driver(Net protocol /All java Driver)

d) Type-4 driver(native protocol/ All-.java driver)

e) Type-5 driver(No nick name) (Not officially confirmed by Sun

Ms)

All odbc drivers and some jdbc drivers (type2) locate and

communicate with Db software by using vendor DB library.

In windows environment this vendor db library comes in the

form of .dll file along with Db software installation. (in oracle

it is oci.dll)

Every odbc driver and every vendor db library is specific to one

DB software.


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Advantages

One Type-1 driver can interact multiple database software by

taking the support of odbc drivers , vendors db libraries

Since odbc drivers ,vendor db libraries are available for all db

software we can use this driver to interact with All Db software

This is built-in driver of jdk so there is no need of arranging this

driver separately.

Disadvantage

This driver performance is poor so not suitable for big

application.

Since vendor DB libraries are required at client side we cannot

use driver for untrusted applet to DB software communication.

This is not industry standards jdbc driver.

Suitable for testing apps

Removed from jdk from java 8 onward.

This driver must be arranged separately.


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Applets are two types:-

1) Trusted Applet

(it perform read and write operation on file system.

2) Un-Trusted applet

Can‖t perform read and write operation on file system.(No virus).

When we install either complete oracle or client oracle (that

contains only sql plus we will get vendor db of oracle).

Type-2

Advantages: -

1) No odbc drivers are required


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2) Gives little bit good performance compare to type-1 driver.

Disadvantage

1) This driver performance is not good for large scale projects.

2) Since vendor DB library is required ate client side, this

driver cannot be used for untrusted applet to dB software

communication.

3) This driver is not industry standard diver.

4) For every DB software we need separate type-2 jdbc driver.

Type-4

Advantages:

1) This gives good performance compare to type-1, type-2

divers and suitable for large scale project

2) Totally developed in java so it is platform independent.


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3) No odbc drivers, vendors DB libraries are required at client

side so this driver is suitable for untrusted Applet to DB

software communication.

4) This driver can be downloaded dynamically to our

computer from internet.

5) This driver industry standard driver.

Disadvantages;

1) For every DB software we need separate tupe-4 driver

3)

We must arrange these drivers separately

Jdbc connection pool is a factory that conatains set of readily available

jdbc connection objects before actually ebing used. The advantage are:

Gives reusability of jdbc objs.

With min number of jdbc connection objects we can make max

clients to interact with DB software

Programmers need not to worry about creating, managing and

destroying jdbc con objs, All These operations will be taken care

by jdbc connection pool.


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All connection objs of jdbc con pool represents connectivity with

same DB software.

Jdbc con pool for oracle means all con objs represents

2015-03-11

connectivity with same oracle dB software


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w.r to diagram

1) Server uses type-1/2 /3/4 driver to interact with database s/W

And create jdbc con objs in the jdbc con pool

2) Client app uses type3 driver interact with server and to get con

obj from jdbc con poo.

3) Client uses that con obj to create other jdbc objs and to develop

persistence logic

4) Client app releases the con obj back to jdbc con pool and that obj

becomes free to give service other clieents.

Proxy dummy item that represent present until real items come.

Proxy server talks with the database s/w on behalf of client

applications

There are two types of connection

a) Direct jdbc connection (created by porgrammser manually)

Class.forName(“…….”);


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Connection con=DM.getConnection(-,-,-);

b) Pooled connection(Gatherred from jdbc conn pool)

For related information of all jdbc drivers refer page no-8 to16

What is jdbc driver that u have used in project if your project is

standalone/desktop app talking with database s/w or two-tier app

running outside the server (webserver/proxy server) then use type4/5/

jdbc driver

If u r project web application, enterprise app, 3-tier app , n-

tier app running from the server then use type 3 with type4 or

type3 with type5 jdbc direr

Note: - Here type 4/5 driver will be user dot create jdbc con

objs in jdbc con pool and type3 driver will be used to get conobjs from jdbc con pool.

Q: -What is the difference between path and class path?

Ans: -

PATH:

It is OS command , can be used in all languages and technologies.


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To make .exe, .bat, .cmd files of certain folder executable from

any location of computer we need to worik with PATH

environment variable (without doing physical copying)

It is not java command, so it can be use anywhere.

-

Example:-

Problem: -

E:\Demo

|run.bat

Run.bat

Date

Time

Ver

DirE:\Demos?run.bat(success)

E\>run

Run is not an internal or external command (problem)

Solution

………….

Add the address of run.bat (E:\Demos) to PATH environment

variable.

Computer propertiesadv sys settingsenvironement

variablesuser/system variables


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Variable name: PATH

VALUE:E:\Demos;;.

od(3)

D:\Demos>run(success)

E:\run Run (success)

Batch(.bat) allows us to group set of commands into single unit.

Javac, java, javap, javah and etc.. are the .exe files of

\bindirectory, so to use them from any folder

our computer we need to add\bin directory to

PATH environment variable.

Important points about environments variable

1) These names are not case sensitive

2)

Do not value to environment variables form cmd prompt,set form mycomputer prompt

3) Separate multiple values added to environment variable

with “;” symbol

4) User variable are specific to currently logged in windows

user, system variables are common to all windows users.

5)

New values added to environment variables are not visible

old cmd prompts

6) Always add new values at the beginning of existing values.

2015-03-12


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classpath

if java app uses new apis or third parties apis then the new

api/third party related directories or jar files must be added to

classpath in order to make java tools (javac ,java, ….) recognizing

and using those apis.

It is a java command and cannot used outside the java.

Example

Problem:

User-defined API /third party api

E:/Demo1

|wish.java

Wish.jva

package con.nt;

public class wish{

public String sayHello()

{

return “good morning”;

}//>javac – d . wish.java

}

Main App

MainApp.java


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Import com.nt;

Public class MainApp

{

Public static void main(String args[])

{

Wish w=new Wish();

System.out.println(“w.sayHello());

}}

D:\work> javac MainApp.java(x)

Error: Can not find symbols com.nt, wish, sayHello

Solution: The address location of “com.nt” pkg(E:\Demo) folder to

ClassPath Environemnt variable.

ClassPath value=E:\Demos1;.

Ok(3).D:\work>javac MainApp.java(success)

D:\work>java MainAp(success)

Jar file: jar archieve file(java level zip file)

Creating jar file representing apis

E:\Demos1>jar cf NtLib .

C =create jar file.

F=specify the jar file name.

To see content of the jar file

E:\Demos1\jar tf NtLib.jar


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tGives table of content.

Adding jar file to classpath

Variable name :CLASSPATH

Value:E:\Demos1\NtLib.jar;;

Ok(3).

We can also add NtLib.jar file to \jre\lib\ext folder.

D:\work>javac MainApp.java

D:\work>Java MainApp

Note : types of class loader

CLASSPATH \JAR\LIB\EXT

FOLDER

Allows both directory, jar file Allows only jar file

Visible to multiple installation of

jdk.

Specific to each jdk.

New values are not visible in old

command prompt

Visible to old command p

These values will be used by

System class loader

These values will be used by

extension class loader.

Set of packages together is called one api.

Set of apis together is called one library.


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Jar files represent libraries.

There are 3 classloaders in jar

(a) To load the classes from jdk libraries (rt.jar)

(b) Extension ClassLoader

To load the class from the libraries of

\jre\lib\ext folder

© System classLoader

To load the classes from the libraires (directories/jar files)

added to CLASSPATH environment variable.

How can you execute java app any folder of a computer?

Add the address location of a .class file to CLASSPATH

environment variable.

D:\Work

|

TestApp.javaTestApp.java

Public class TestApp

{

Public static void main()

System.o.pln(“hello”);

}

}

D:\work> jvac TestApp.java

Variable name classpath value:D:\work1:


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What is the difference between physical database s/w and logical

database.

Logical db is a logical partition of physical db s/w .Each logical DB

contains Db tables , pl/sql procedures, function and tec…

In one physical DB s/w (like oracle ,mysql) we can create

multiple logical DBs for multiple projects of a company on 1

per project basis.

In oracle we get one default logical DB and it is identified with

its SID(Service id).


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We call type-1\type-2 jdbc drivers as thick drivers because

they need more component at client side while using.

We call type4\type5 jdbc driver as thin drivers because they

directly talk with DB s/ws without taking support any

components.

The oracle corporation SUPPLIED TYPE2 JDBC DIRVER FOR

OR CALE ID CALLDED “Oracle Oci driver”.

The Oracle corporation supplied type4 jdbc driver for oracle is

called “Oracle thin driver”.


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(oracle corporation supplied type-4 mechanism based jdbc driver for

oracle)

Mechanism : type 4

Target Database software: oracle

Jdbc driver class: oracle.jdbc.driver.OracleDriver (0r)

oracle.jdbc.OracleDriver

Jdbc url:

jdbc:oracle(protocol)thin(subname):@:(host name

and port number of oracle):

Jar files:

oracle 8i:classes111.jar

oracle9i: classes12.jarOracle10g:ojdbc14.jar

oracle11g:ojdbc6.jar.

Most of vendor are giving jdbc drivers in the form of jar file as

shown above

All software installed in our computer will reside in different

s/w ports. Every s/w port is identified with its port number. In

windows operating system based computer we have 65535

software ports in that 1024 are reserved for operating system


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services. All externally installed software will run on other

ports in the range 1025 to 65535;

Oracle default port no: 1521

MySQL default port no :3306

To refer a computer being from that computer we use the term

“localhost”.

Procedure to develop jdbc Application by using oracle thin

drive.

Step-1) Gather oracle thin driver details.

Step-2)Add odbc14.jar or odbc6.jar file “classpath”.

Variable name: Classpath or in \jar\lib\ext

folder

Full path:- C:\Program Files\Java\jdk1.7.0_76\jre\lib\ext\[past here]

Value:c:\orcleexe\app\orcle\porduct\10.2.0\server\jdbc\lib\odbc14.jar;;.

--ok(3).

Step3> Develop jdbc App using oracle thin driver

SelectTest.java

……………….

……

……….same as previous app


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………but write following lines of code to register jdbc driver and to

establish the conncection.

//register oracle thin driver with DriverManager service

Class.forName(“oracle.jdbc.driver.OracleDriver”);

//establish the connection

Connection

con=DriverManager.getConnection(“jdbc:oracle:thin:@localhost:1521:

xe”,”scott”,”tiger”);

jdbc:oracle=protocol

thin=subname

:@localhost:1521 host name and port no

Setp4:-

Work with Oci driver details(oracle corporation supplied type2 mechanism based jdbc diver for

oracle)

Driver class name: oracle.jdbc.driver.OracleDriver (or)

oracle.jdbc.OracleDriver

url: jdbc:oracle:oci8:@

jar file : Same as thin diver.

Example application:

All steps are same as oracle thin driver but use the following jdbc url in

DriverManager.getConnection (-,-,-) method.


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Connection con=DriverManager.getConnection

(“ jdbc:oracle:oci8:@xe”,”scott”,”tiger”);

( jdbc:oracle) protocol

sid(xe)

If the subname is “thin” in the URL then the “oracle thin” driver

will be used to establish the connection.

If the subname is “oci8” in the URL then the “oracle oci” driver

will be used to establish the connection.

Jar file added to the classpath are not visible to the projects

created in the IDE but the jar files added to the

java_home\jar\lib\ext folder are visible to the same.

To add jar file (like ojdbc14.jar) to the project of Eclipse IDE

use Right click on the project

Build path

add externalachieves browser and select the jar file (ojdbc14.jar)

While working with any jdbc driver we need to gather

a) Driver class name

b) Jdbc url

To create jdbc conn pointing to any database s/w we need 4

jdbc properties

a) Driver class name

b) Jdbc url

c) Database user name


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d) Database password

The class name of jdbc object will change based on the jdbc

diver we use so we never specify them in our Apps but we

refer the object of those classes by using common jdbc api

interface reference variables.

Java.sql.Statement(I)

^

|extends

Java.sql.PreparedStatement(i)

^

| extends

Java.sql.CallableStatement(I)

There are 3 statement object in jdbc programminga) Simple statement object

(it is the object of jdbc driver supplied java class that

implements java.sql.Statement(I));

b) PreparedStatement object


implements java.sql.PreparedStatement object.

c) CallableStatement object


implements java.sql.CallableStatement. object


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2014-03-14

LoginAPP

Checks identity of a user by taking the given username and password

details .Also verifies them against Database table.

DB table in oracle

Saq> create table userlist(uname verchar2(20), pwd verchar2(20));Sql> insert into userlist values(―raja‖,‖rani‖);

Sql> insert into userlist values(―king‖,‖kingdom‖);

Sql Query of the Application

Sql> select count(*) from userlist where uname=‖raja‖ and pwd=‖rani1‖

Count(*)

0 (Invalid credentials)

LoginApp.java(refer page no-26 application no-8)

What is sql injection problem?

Changing the behavior or sql query and application by adding special

sql instruction (like --) to the query along with the input values is

called raising sql injection problem. Hackers use this technique to get

into various accounts by supplying correct user name and wrong

password.

Respect to application -8 of booklet.


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Java LoignApp

Username :‖raja‖ - -

Password: hyd (wrong password)

Output : valid credentials (sqlinjection problem)

In real scenario persistence logic will not be placed directly in main

application like main method persistence will be placed in separate

class called DAO class (Data Access Object class) the java class that

separate persistence logic form other logic it makes that logic as

flexible logic to modify and also has reusable logic is called DAO class.

JdbcProj2

| src

|com.nt

|StudentDAo.java

|MainApp.java

package com.nt;

import java.sql.*;

public class StudentDAO

{


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Connection con=null;

public void makeConnection()

{

try{

Class.forName("oracle.jdbe.driver.OracleDriver");//establish the connection

con=DriverMananager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","scott","tiger");

}//try

catch(Exception e)

{


}//catch

}//makeConneciton()public void getStudentDetails(String city)

{

try{

Statement st=null;

if(con!=null)

st=con.createStatement();

ResultSet rs=null;

if(st!=null)

rs=st.executeQuery("select * from students where sadd="+"'"+city+"'");

if(rs!=null)

{

while(rs.next())

{

System.out.println("rs.gtInt(1)+" "+rs.getString(2)+" "+rs.getString(3));

}//while

}//if

//close objsif(rs!=null)

rs.close();

if(st!=null)

st.colse();

}//try


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catch(Exception e)

{


}

}//getStudntDetailspublic void closeConnection()

{

try

{

if(con!=null)

con.close();

}

catch (Exception e){


}

}//close connection

}//class

package com.nt;

public class MainApp

{

public static void main(String args[])

{

//create obj DAO class

StudentDAO dao=new StudentDAO();

//call mehods

dao.makeConnection();

dao.getStudentDetails("hyd");dao.closeConnection();

}//main

}//class


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Assignment:

Q: = By using DAO style implementation get the emp details form emp

table who is having given nth highest salary.

When java app sends sql query to databse software ,the database engg of database s/w performs 3

operations on that SQL Query

1.

Parse operation

2. Execution operation

3.

Fetch operation

Parse-> In this operation the given query will be splited into tokens and the syntax of the query

will be verified by compiling SQL QUERY;


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EXECUTE: - The Parsed Query will Optimized and will be executed in database software.

Fetch: - The results of executed SQL Query will be gathered from database software and will be

sent to java application client application.

Simple Statement obj sends raw/static SQL Query to database software , i.e given query goes

to database software directly wit out any conversions.

When use simple statements object to execute same SQL Query in database software for

multiple times either with same values or different values.

a) Same Query goes to database s/w for multiple times from java application.

b) Same query will be parsed in db s/w for multiple times.

c) Same query will be executed in db s/w for multiple times either with same values or diff

values.

d)

Same query output will be fetched out from db s/w for multiple times.

Performing a), b) operation on same query for multiple times is unnecessary, But

performing c), d) operations on same query for multiple times is necessary, but we can

avoid a), b) operation happing for multiple times when we work with simple statement

object, Due to this we can say simple statement object is not suitable for executing same

query for multiple times with different values or same values.

Example:-

Railway Resrervation App that book 100000 tickets per day should execute same inser query for

`100000 times to maintains passenger details.

a) Same insert query goes to Db s/w from java app to database software for 1,00,000 times:

100000*0.1=10,000sec

b) Same insert query will be parsed in database software for 100,000 times:

1,00,000*0.1sec=10,000secs

c) Same insert queruy will be executed in database software for 1,00,000 times wither with same

or diff values:100000*0.1=10,000secs

d)

Same insert query output will be fetched out for 100000 times : 100000*0.1=10,000secs

Performing a), b) operations on same for multiple times is unneccassary on same query, but this

cannto be avoided while working with simple statement object..


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Limitations with simple statement object

Not suitable to execute same query multiple time either with same values or different values (

Gives performance problem)

May Raise SQL injection problem.

Framing query by involving variable sin complex because

we need to convert java values to sql values in this process.

Inserting date values in the in database table by collecting

values date values in different pattern in complex process.

Inserting large object (files) is not possible.

Improves network traffic between java application and

database s/w .

To overcome all these problem we need to work with per-

compiled sql query with support of jdbc

perparedSatement objcect.

Pre-compiled sql query/Dynamic sql query

The sql query tahat goes to db s/w from client app with

or without values and becomes parsed or comiledirrespective of ites executeon is called per-compiled sql

query.


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Jdbc prepaearedStatement object represents this per-

compiled sql queryo of sb s/w being from java app and

this oject can be useda) To assing multiple set of values to query params.

b)

To execute query for multiple times either with same

values or diff values

c) To fetch the query results for multiples times.

Simple Statement object deals with static /raw sql

query where as PreparedStatement obj with pre-

compiled sql query.

The above Railway ticket reservation example with

PreparedStatement obj

a) Insert query oges to Db s/w from java app only for one

time :1*0.1=0.1 sec

b) Insert query will be parsed /compiled in databse s/w only

for one time : 1*0.1=0.1 sec


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c) Java app assigns multiple sets values to insert sql query

and executes that query for multiple times either with

same or different values :1,00,000*0.1=10,000 secsd) Same insert query output will be fetched out for multiple

times: 1,00,000*0.1=10,000secs

Here a), b) operations are taking place on insert query only 1

time. This improves performance.

PreparedStatment object suitable for executing same

query for multiple times either with same values or

different.

Based on the above discussion we can say PreparedStatement

objet is useful in the development of ticket reservation,

registration and search activities related application

development.

Procedure to work with PreparedStatement object;-

Step-1 ) Prepare SQL Query with place holders /parameters (?)


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String qry=”insert into students values(?,?,?)”;[parameters

represent (?) Positions in sql query for which values can be set

latter]

Setp-2) send sql query to DB s/w and make that query as per-

compiled sql query in database s/w and get PreparedStatement

representing that per-compile object query.

PreparedStatement ps =con.prepareStatement(qry);

Con.prepareStatement(0) method

a) Sends given SQL Query to DB s/w

b) Makes DB Engg to compile/parse that Query and also to

make that query as per-compiled SQL Query.

c) Create and Returns PreparedStatement object back to java

application representing pre-compiled sql query of

database s/w.

Step: -3) set values to Query params/place holders(?) of pre-

compiled Query using setxxx(-) methods.Ps.setSPs.setInt(1,1001);

Ps.setString(2,”raja”);


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Ps.setString(3,”hyd”);

Step:-4) Execute the above pre.compiled sql query of

database s/w.

Int result=ps.executeUpdate();

Step5) Process the result.

If(result==0)

Sop(“record not inserted”);

Else

System.out.println(“Record inserted”);

Step: -6) To execute the above query for multiple with diffvalues repeat step3 to step 5 for multiple times.

Step:-7) close jdbc object.

Write a jdbc app to gather and insert n number of stuendts details in

database table


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Here we need to execute same “insert” SQL Query w ith diff values

for multiple times, for this we need to use per-compiled SQL

Query with the support of jdbc PreparedStatement object.

Referr application

IN THE development logic it is always recommended to sql query

at the top of class as constant value(static final variable var)

Ex: -private static final String INSERT_STUDENT_QRY

Don‖t place “*” symbol in select sql query, Always write col names

in select sql query.

Select * from student bad practice( if we add new col in db

table then problem will come)

Select sno,sname,sad from student good practice.

We can use preparedStatement object for both select or non-

select query exection.Pre-compiled query represented by preparedStatment object can

be there with parameters or without parameters.

Executing select query by using preparedStatement object.

PreparedStatement ps=con.prepareStatement(“Select * from Student”);

ResultSet rs=ps.executeQuery();

Whle(rs.next())

{

System.out.println(rs.getInt(1)+””+rs.getString(2)+””rs.getString(3));

}


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While working with jdbc PreparedStatement object we can place

parameters in the sql query just representing input values but we

cannot parameters representing table name, col names and sql

keywords…..

Select * from students (valid)

Select * from student where sno>=? (valid)

Select * from student where ?>=? (invalid)

Select * ? student (invalid)

Select * ? ? where ?>=? (invalid)

Note: - using PreparedStatement object we cannot execute DDL queries

having table name, co names as the parameters.

Q: How can we execute static SQL Query by using PreparedStatement

object?Call ps.execute(-),executexxx(-) methods with agrs on jdbc

preparedStatement object as shown below.

PreparedStatement ps=con.prepareStatement(“Select * from student”);

ResultSet rs=pr.executeQuery(“select * from em”);

While(rs.next()) -- executes as static sql query.

{

..

..


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}

in the above code “select * form student” will not be executed but “select

* from emp” will be executed as static SQL Query.

(Vvi)

What is the difference between simple statement and

PreparedStatement?

Simple statement PreparedStatement

1. Deals with static sql query2. Suitable for executing query for

one time without input values.

3. May raise sql injection problem

4. Makes database engine to compile

sql query with input.

5. Not suitable for date valueinsertion.

6. Not suitable for large object

insertion (files)

7. Improves network traffic b/t java

app and database s/w(degrades

the performance)

8. Using one statement object we

can send and execute multiple sql

queries.

9. We need to convert input values

1. Deals with pre-compiled sqlquery (dynamic query)

2. Suitable for executing query for

multiple times either with same

or different input values.

3. Does not raise sql injection

problem.4. Makes database engine to

compile without inputs.

5. Suitable for date value insertion

6. Suitable

7. Reduces n/w traffic b/t java app

and database s/w and improves

performance

8. For every sql query we need to

separate PreparedStatement

object.


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of query according to sql syntax. 9. Conversion is not required.

Why simple Statement object raises sql injection problem and why sam

problem does not raise in PrepasredStatement.

Simple Statement obj makes the DB engine of Database software to

compile sql query with input values, so the special sql instruction (like

--) that are given along with input values participate in query

compilation, due to the sql query behavior will be changed during

execution because of those special sql instructions (--) this is nothing

but sql injection problem

PreparedStatement object makes the Database Engine of Database

s/w to compile sql query without input values and input values

will be set to query after the compilation of query and before the

execution of the query, so he special sql instruction (like --) that

are given along with the given values does not participate in

query compilation, Due to this they cannot change query

behavior in the execution of query. This indicates “NOA=sql

injection problem.

MySQL


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TYPE: Database Software

Version: 5.5

Vendor: DevX/sun Microsystem/Oracle Corporation

Open Source

Port no: 3306

Default user-name: root

Password : root (will be chosen during the installation)

Download: -

www.oracle.com , www.mysql.com

Allow to create logical DBs.

procedure to create logical database having DB table with

records.

Step-1) Launch mysql prog

Start mysql mysql 5.5 command line client

Password (root) which is choosen during installation

Setp2) create Logical DB NTDb1

Mysql> Create database NtDB1;

Step-3) create database table student in NtDb

|no int

|sname varchar

|sadd varchar

Connect NtDb5

http://www.oracle.com/http://www.oracle.com/http://www.mysql.com/http://www.mysql.com/http://www.mysql.com/http://www.mysql.com/http://www.oracle.com/


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Create table student (sno int(5),sname, varchar(20) ,sad

varchar(20))

Insert into student values(111,‖ramesh‖,‖hyd‖);

Commit.

DevX supplied type4 mechanism based jdbc driver for mysql is

called Connector/j jdbc driver and This driver details are

Driver class name: org.gjt.mm.mysql. Driver(0r)

com.mysql.jdbc.Driver

url: jdbc:mysql:///


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Procedure to use SQLY0G for MySQL logical DB having DB table

with records.

Launch sqlyog

continue

new (con1)hostaddress(localhost)Username-root password rootconnect

right click on root crate database (NtDb6)[name of logical

database]createNtDb6(right click)create table

Field name Datatype len

Pid Int 5

right click on tableinsert record

Assignment

Develop jdbc app that transfers the record from oracle db table to

my sql table.

Working with date value 2015-03-19

While developing various apps we need to insert DOB, DOJ,

DOMarriage, Bill Date, Expiry date Purchase Date and etc…

values Database table along with other values.


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Inserting date values as string values in DB table cols is notrecommended because we cannot compare two values and

we cannot subtract one date values from another date values.

It always recommended to insert date values in “Date data

type columns of DB table.

Different database s/w support different patterns of date

values.

Oracle: dd-MMM-yy (10-OCT-80)

Mysql: yyyy-MM-dd (1980-10-20)


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If we use simple statement object to insert date values we

must place date value in the query in the pattern which is

supported by DB s/w.

If we use PreparedStatement object to insert date value, we

need to give java.sql.Date class object to jdbc driver through

SQL Query and driver inserts date value in dB table in pattern

that is supported by underlying database s/w.

java.util.Date is the super class of java.sql.Date class and it

cannot be used to perform Database operations.

java.sql.Date can be used to perform DB operations….

If you set java.sql.Date class object to jdbc driver representing

date value then jdbc driver inserts the date value in the

pattern it supported by underlying database s/w.

Example application to retrieve different date pattern value and insertthem in database table.

Refer app-10

Person_tab(in oracle)

Ask data of birth from end user and calculate his age.

To retrieve date values from DB table we can use either

Simple Statement object or PreparedStatement object.

To retrieve Date values form jdbc ResultSet object we can use

rs.getDate(-) method.


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TO convert java.util.Date class object to String date value use

format.

(1) App executes select query using simple Statement or

PreparedStatement object and get ResultSet object having Date

values in the form of java.sql.Date class obj.

(2) Application retrieves java.sql.Date class object to java.util.Date

class object.

(3) Application Converts java.sql.Date class objects to java.util.Dateclass object.

(4) Application uses format(-) of SimpleDateFormat Date class to

convert java.util.Date class object to String date values.


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(5) App gives this date value to end user.

For above diagram based application refer

If u use rs.getString() method to retrieve date value display in

yyyy-MM-dd pattern.

If you use rs.getDate() method to retrieve value there is possibility

of displaying date value in the pattern that we need.

parse() method of SimpleDateFormat class converts given String

date values ot java.util.Date class object.

format(-) of SimpleDateFormat class convers given java.util.Date

class obj to string date value.

//Agecal.p

import java.util.*;

public class AgeCalApp{

public static void main(String args[])

{

Scanner sc=new Scanner(System.in);

System.out.println("Enter DOB(dd-mm-yyyy)");

String dob=sc.next();

//convert string date value into java.util.Date class object.

SimpleDateFormat sdf1=new SimpleDateFormat("dd-MM-yyyy");

Date udob=sdf1.parse(dob);


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//get Sys date

Date sysdate =new Date();

//calc age

long ms=(sysdate.getTime()-dob.getTime());

//long ms=System.currentTimeMillis()-udob.getTime();

float age=(float)ms/(1000.0f*60*60*24*365);

System.out.println("Age" +age);

}

}

Q: - Write a jdbc application to copy records from students

records form MySQL to student table of oracle.

Here to get all records mysql student table we need to execute

“select *form Student” only for time without any input values ,

for this we need to use SimpleStatement object. To insert the above multiple records in student db table of

Natraj Jdbc

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