Embedded SQL Embedded OQL (Jasmine ODQL)

nikos dimitrakas IS4/2i1242/2i4042 spring 2007 1

Embedded SQLEmbedded OQL (Jasmine ODQL)

Chapter 21 + 28.8 in third edition

Chapter 29.7 + Appendix E in fourth edition

Article: SQLJ: It’s Javalicious!

Chapter 8 in ”Principles of Database Systems with Internet and Java™ Applications”

Excerpt from ”Database Systems the complete book”

Jasmine On-line Documentation

ODMG 3.0 / ODMG 2.0(Chapter 26 in third edition / Chapter 27 in fourth edition )


What is embedded SQL?

• Host Language– Any programming language

• Database– An SQL database (relational database)

• Embedded SQL:– Helps the host language communicate with the

database via SQL


Why embedded SQL?

• Advanced logic

• Database Interface/Application


Static vs. Dynamic

• Static embedded SQL– Compiled in advance Faster at run-time– Limited functionality

• Dynamic embedded SQL– Not compiled in advance Slower– Full functionality

Everything that can be achieved with static embedded SQL, can also be achieved with dynamic embedded SQL


Standard embedded SQL vs. embedded SQL for Java

• Standard embedded SQL– Static– Dynamic

• Embedded SQL for Java– Static (i.e. SQLj)– Dynamic (i.e. JDBC)


Standard embedded SQL

• Defined for a number of ”older” languages:– ADA– C– COBOL– FORTRAN– PASCAL– PL/1

• ISO standard


Standard embedded SQLBasics

All SQL-commands start with

EXEC SQL

And are terminated with the appropriate command-terminator (t ex ;) based on the host language


Standard embedded SQLExample (singleton select)

…

EXEC SQL CONNECT myDB;

EXEC SQL SELECT name, address

INTO :lname, :laddress

FROM myTable

WHERE id=53;

…


Standard embedded SQLExample

BeginEXEC SQL DECLARE mycursor CURSOR FOR

SELECT name, petFROM Person, PetWHERE Person.name = Pet.name;

. . .EXEC SQL OPEN mycursor;. . .EXEC SQL FETCH mycursor INTO :lname, :lpet;While SQLCODE = 0 DoBegin

Writeln(lname, lpet);EXEC SQL FETCH mycursor INTO :lname, :lpet;

End;. . .EXEC SQL CLOSE mycursor;

End.


Standard embedded SQLExempel

VAR query : CHAR(1000);. . .query := ’DELETE FROM Employee WHERE enumber =

’0025’;

EXEC SQL PREPARE statement FROM :query;EXEC SQL EXECUTE statement;

query := ’DELETE FROM Employee WHERE enumber = ’0026’;

EXEC SQL EXECUTE IMMEDIATE :query;

tablename := ’myTable’;query := ’DELETE FROM :tablename;EXEC SQL EXECUTE IMMEDIATE :query;


Java embedded SQLGeneral

• Java program

• JDBC driver

• (JDBC-ODBC bridge + ODBC driver)

• Database


Java embedded SQLArcitecture

Java Application

JDBC driver manager

DBMS

JDBC/ODBC bridge

ODBC Driver

JDBC Driver (DBMS Specific)


JDBC sequence

1. Import Packages 2. Register JDBC Driver3. Open a Connection to the database4. Create a Statement5. Execute an SQL command and receive a Result Set

(if there is one)6. Process/Work with the Result Set (back to point 4) 7. Close the Result Set and the Statement8. Close the Connection


1. Import Packages

//Import packagesimport java.sql.*; //JDBC packages

//other packagesimport java.util.*;…

java.sql package specification:http://java.sun.com/j2se/1.5/docs/api/index.html


2. Register JDBC Driver

//Load IBM DB2 driverClass.forName (”com.ibm.db2.jcc.DB2Driver”);

//Load JDBC-ODBC driver bridgeClass.forName(”sun.jdbc.odbc.JdbcOdbcDriver”);

// Load Oracle driverDriverManager.registerDriver (new oracle.jdbc.driver.OracleDriver());


3. Open a Connection to the database

String userID = ”dbuser”;String password = ”abc123”;String ODBCURL = ”jdbc:odbc:mydb”;String ORACLEURL = ”jdbc:oracle:mydb”;String DB2URL = ”jdbc:db2:mydb”;

Connection con1 = DriverManager.getConnection (ORACLEURL, userID, password);

Connection con2 = DriverManager.getConnection (ODBCURL, userID, password);

Connection con3 = DriverManager.getConnection (DB2URL, userID, password);

con3.setAutoCommit(true);


3. Open a Connection to the database, cont.

The URL (”database address”) is compised of three parts:

jdbc:databasetype/ODBC:databasename/ODBC-alias

ODBC-aliases can be defined in

the ODBC Manager (”Data

Sources (ODBC)” in the

Administrative Tools in the

Control Panel or by running

odbcad32.exe found in system32):


4. Create a Statement

PreparedStatement pstmt1 = con1.prepareStatement ("SELECT hotelname, rating FROM hotel WHERE city = ?");

pstmt1.setString(1, ”Hawai”);

PreparedStatement pstmt2 = con1.prepareStatement (”UPDATE event SET place = ? Price = ? WHERE activity = ?");

pstmt2.setString(1, ”beach”);

pstmt2.setInt(2, 100);

pstmt2.setString(3, ”swimming”);


5. Execute an SQL command and receive a Result Set (if there is one)

//execute the prepared statement pstmt1 and store the result in a result set

ResultSet rs = pstmt1.executeQuery();

//execute the prepared statement pstmt2

pstmt2.executeUpdate();


6. Process/Work with the Result Set

// Print a list of the hotels that were returned by the query

System.out.println(”Hotels in Hawai:”);

while (rs.next()){ System.out.println (rs.getString(”hotelname”));

}

//Alternatively

rs.getString(1)


7. Close the Result Set the Statement 8. Close the Connection

// close the result set, statements, and the connections

rs.close();

pstmt1.close(); pstmt2.close(); con1.close();

con2.close();

con3.close();


Data types

It is often necessary to map the database data types to the Java data types/classes:

• SQL integer can be mapped to Java int• SQL number, real etc can be mapped to Java real• SQL varchar, char, string etc can be mapped to Java

String• SQL date, time, timestamp etc can be mapped to Java

java.sql.Date, java.sql.Time, java.sql.Timestamp


SQLJ

SQLJ uses and extends the JDBC infrastructure.

It uses contexts in order to distinguish connections

All SQLJ database commands start with #sql

It creates profiles that contain information about the SQL commands (so that they can be handled as static commands)

SQLJ Java packages: sqlj.runtime


SQLJ architecture


SQLJ sequence

1. Import Packages

2. (Define iterator)



5. Set DefaultContext / other Context

6. Execute an SQL command and receive the result (if there is any)

7. Process/Work with the result (cursor)

(back to point 6)

8. Close the cursor

9. Close the Connection/Context


1. Import Packages

//Import packagesimport sqlj.runtime.*;import sqlj.runtime.ref.*;

import java.sql.*; //JDBC packages

import java.util.*;

sqlj package specification:ftp://ftp.calweb.com/business/sqlj/SQLJ-P0.pdfhttp://www.ifis.mu-luebeck.de/lehre/ss99/prakt/informix-jdbc-doc/sqlj/doc/runtime/javadoc/packages.html


2. (Define iterator)

#sql iterator Hotel_Cursor (String hotelname, Integer rooms) ;

#sql iterator String2_Cursor (String, String);



//Load IBM DB2 driverClass.forName (”com.ibm.db2.jcc.DB2Driver”);

//Load JDBC-ODBC driver bridgeClass.forName(”sun.jdbc.odbc.JdbcOdbcDriver”);

// Load Oracle driverDriverManager.registerDriver (new oracle.jdbc.driver.OracleDriver());



String userID = ”dbuser”;String password = ”abc123”;String ODBCURL = ”jdbc:odbc:mydb”;String ORACLEURL = ” jdbc:oracle:mydb”;String DB2URL = ”jdbc:db2:mydb”;

Connection con1 = DriverManager.getConnection (ORACLEURL, userID, password);

Connection con2 = DriverManager.getConnection (ODBCURL, userID, password);

Connection con3 = DriverManager.getConnection (DB2URL, userID, password);

con3.setAutoCommit(true);


5. Set DefaultContext / other Context

// Set the default context so SQLJ can automatically pick up the connection

DefaultContext ctx = new DefaultContext (con3);

DefaultContext.setDefaultContext (ctx);



int rooms = 500;

String name = ”Grand";

String city = ”Madrid”;

#sql { INSERT INTO hotel (hotelname, rooms, city) VALUES (:name, :rooms, :city) };



String city = ”Rome”;Hotel_Cursor hotelcursor;

#sql hotelcursor = {SELECT hotelname, rooms FROM hotel WHERE city = :city };

String2_Cursor hotel200cursor;

#sql hotel200cursor = {SELECT hotelname, city FROM hotel WHERE rooms >= 200 };



// Print a list of the hotels that were returned by the first query

System.out.println(”Hotels in Rome:”);

while (hotelcursor.next())

{

System.out.print(hotelcursor.hotelname());

System.out.print(” ”);

System.out.println(hotelcursor.rooms());

}


// Print a list of the hotels that were returned by the second query

String s1;String s2;

System.out.println(”Hotels with 200 or more rooms:”);while (true) { #sql { FETCH :hotel200cursor INTO :s1, :s2 }; if (hotel200cursor.endFetch())

break; System.out.println (s1 + "\t” + s2);}



8. Close the cursor9. Close the Connection/Context

// close the cursors and the connection/context

hotelcursor.close(); hotel200cursor.close(); ctx.close(); //this will close the connection con3 as well

ctx.close(false); //keep the connection alive

con3.close(); //close only the connection


More information

• JDBC (SUN):

http://java.sun.com/products/jdbc/index.html

• SQLJ:

http://www.sqlj.org/


OQL, ODQL & embedded OQL, ODQL

• Hard to define a border

• Depends on the OODBMS

• compare SQL – Stored Procedure – Embedded SQL


Embedded OQL/ODQL

• OO programming language– Java– C++– …

• OODBMS– Jasmine– Objectivity– FastObjects– …

• Classes– Database specific classes, or– JDO Classes and JDO enhanced database classes

• Query Language– Database specific query language, or– JDOQL


Embedded OQL/ODQL Architecture

JDO classes

OODBMS

Java Application

Database Java Classes

OODBMS-specific classes

JDO Enhanced Database

Java Classes


OQL (example)

select e.ssn, count(e.teaches) from e in Instructorwhere e.dept.name = "D1" and count(e.teaches) > 0

select Instructorfrom Instructorwhere Instructor.dept.name = "D1”and Instructor.teaches.count() > 0


Embedded OQL (C++)

#include ……%for each v in select e.ssn, count(e.teaches)

from e in Instructor where e.dept.name = "D1" and count(e.teaches) > 0

do %print v;


Jasmine ODQL

defaultCF …;…Instructor set vs, v;vs = select Instructor from Instructors

where Instructor.dept.name == "D1”and Instructor.teaches.count() > 0;

scan (vs, v){

v.ssn.print();v.teaches.count().print();

};end;


Embedded Jasmine ODQL i Java

import jp.jasmine.japi.*;…db = new Database();…ODQLStatement odql = db.getODQLStatement();odql.defaultCF("myCF"); odql.execute("Instructor set vs;");odql.execute("vs = select Instructor from Instructor

where Instructor.dept.name == \"D1\" and Instructor.teaches.count() > 0;");

DBCollection instructors = (DBCollection) odql.getVar(“vs");

Enumeration instructorsEnum = instructors.elements();


Embedded Jasmine ODQL i Java

odql.execute("Instructor v;");while (instructorsEnum.hasMoreElements()) {

DBObject v = (DBObject) instructorsEnum.nextElement();String ssn = (String) v.getProperty(“ssn");System.out.println(ssn);odql.defineVar("amount", new Integer(0));odql.setVar("v", v);odql.execute("amount = v.teaches.count();");System.out.println(odql.getIntVar("amount"));

}


Jasmine ODQL

ODQL (Object Definition and Query Language) is an integrated object language that provides facilities for object definition, object manipulation and object query. ODQL statements can either be embedded and compiled in a host language, or interpreted using the supplied ODQL interpreter


Jasmine ODQL (structure)

defaultCF database name

Variable declaration

Program code

end;

All commands must be terminated with ;


Jasmine ODQL (common constructs)

if (condition) {program

code};else {program

code};scan (set, element variable) {program code};

while (condition){program code};


Jasmine ODQL (useful methods)

Set methods:

unique()hasElement(element)hasSameElements(set)union(set)count()…

User defined methods:

Can be defined for a class!

For example:age() can be a method

defined for the class Person and it calculates the person’s age based on the date of birth.


Jasmine ODQL (example)

defaultCF myCF;

Person set ps, p;Job set js, j;Integer totalsalary;

/*All people that live in Stockholm and are over 18*/

ps = select Person from Person where Person.age() > 18 and Person.homeaddress.city == "Stockholm";


Jasmine ODQL (example cont.)

scan (ps, p){

totalsalary = 0;p.name.print();p.isRich().print();p.jobs.count().print();js = p.jobs;scan (js, j){

totalsalary = totalsalary + j.salary;j.description.print();j.salary.print();

};totalsalary.print();

};end;


Jasmine Java support classes (J-API)

• Database – Manages database sessions and transactions.

• DBObject – Supports instance-level operations, such as manipulating properties

and invoking methods.

• DBClass – Supports class-level operations, such as manipulating properties and

invoking methods.

• DBCollection – Supports Jasmine collections.

• ODQLStatement – Supports executing ODQL statements and manipulating ODQL

variables.


Jasmine J-API sequence

1. Import Packages


2a. Start a session and a transaction

3. Get an ODQL Statement object

3a. Set the default Class Family

4. Execute ODQL statements or other commands through the ODQL statement object

5. Work with data in Java

(back to 4)

6. End the transaction, session and connection


1. Import Packages

import jp.jasmine.japi.*;


2. Open a Connection to the database2a. Start a session and a transaction

db = new Database();

db.startSession();

db.startTransaction();


3. Get an ODQL Statement object 3a. Set the default Class Family

ODQLStatement odql = db.getODQLStatement();

odql.defaultCF("CAStore");


4. Execute ODQL statements or other commands through the ODQL statement object

5. Work with data in Java

odql.execute("Customer set vs;");odql.execute("vs = select Customer from Customer where Customer.orders.count() > 2;");

DBCollection customers = (DBCollection) odql.getVar("vs");

Enumeration customersEnum = customers.elements();

while (customersEnum.hasMoreElements()) {DBObject v = (DBObject) customersEnum.nextElement();String name = (String) v.getProperty("name");System.out.println(name);

}


6. End the transaction, session and connection

db.endTransaction();

db.endSession();

db.close();


More information

• OODBMS documentation– Jasmine: Jasmine On-Line Documentation

• Jasmine J-API– Programmer’s Guide for Java Proxies (Jp)

C:\Jasmine\Doc\ODB\jp.pdf

Embedded SQL Embedded OQL (Jasmine ODQL)

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