SQL212 Oracle SQL Manual

Accelerated Computer Training for Working Professionals Factory 2010 Case

Orange Coast Database Associates Course (800)355-9855 or http://ocdatabases.itgo.com

Orange Coast

Database Associates

Specializing in Microsoft Office,

Access, SQL, and related technologies Classes custom designed for Working Professionals

http://www.dhdursoassociates.com

San Juan Capistrano, CA

(800)355-9855

SQL212 Introduction to SQL Using

Oracle

1

Bookstore SQL212 1

An accelerated introduction to SQL for non-programmers

P.O. Box 6142

Laguna Niguel, CA 92607

949-489-1472

http://www.d2associates.com

Welcome to SQL212 –Accelerated Introduction to

SQL with Oracle

Bookstore SQL212 2

Accelerated Introduction to Oracle SQL

• Introduction (s)

• Facilities

• Course Packet (content may vary by class)

– Student questionnaire

– Collaterals (Price List, Flyers, etc.)

– PowerPoint handouts for all sessions (instructor slides may have some changes)

– Evaluation form

– Training certificate

• Website (Terms, Practice Tests, etc.)

http://www.dhdursoassociates.com/glossary.html

http://www.dhdursoassociates.com/on-line-testing.html

2

Bookstore SQL212 3

SQL Curriculum

SQL200*

SQL200S*

SQL212

OracleSQL202

SQL Server

SQL201W

MySQL

* = included in

above courses

Bookstore SQL212 4

Accelerated Introduction to SQL

• Assumes no prior knowledge of SQL or Oracle products

• Quick pace for experienced computer users

• End-user, not programmer, oriented

• SQL212 is an extension to SQL/200

– Uses Oracle in class but is otherwise identical.

• SQL200s is first two modules of SQL200 - a “read only” version.

3

Bookstore SQL212 5


• Select– Basic– Filters– Joins– Subqueries– Unions– Grouping and

Summarization

SQL Covered (Day 1) 9:00AM – 4:00PM:

Bookstore SQL212 6


• Data Updates– Insert– Update– Delete

• Data structures– Create– Drop– Alter– Views– Indexes

SQL Covered (Day 2, 9:00AM – 12:00PM):

4

Bookstore SQL212 7


• Focus is on SQL language

• We will use Oracle SQL Developer in this

class

• Enterprise manager outside scope of this

class

Bookstore SQL212 8


• 3 Sessions• Lecture• Demo• Student “hands-on” • Many exercises are cumulative –

later examples build on queries created earlier

Course Format:

5

Bookstore SQL212 9


• Session 1 – Basic SQL• Session 2 – Multi-table

Retrieval• Session 3 – Modifying Data

Course Schedule (“1/2” day sessions):

Notes

Bookstore SQL212 10

sql200-s1-bk.ppt

sql200-s1-bk.ppt

sql200-s1-bk.ppt

sql200-s1-bk.ppt

sql200-s2-bk.ppt

sql200-s2-bk.ppt

sql200-s2-bk.ppt

sql200-s2-bk.ppt

sql200-s2-bk.ppt

sql200-s2-bk.ppt

sql200-s2-bk.ppt

sql200-s3-bk.ppt

sql200-s3-bk.ppt

sql200-s3-bk.ppt

sql200-s3-bk.ppt

6

Notes

Bookstore SQL212 11

Notes

Bookstore SQL212 12

11/25/2011

1

Bookstore SQL200 Module 1 1

SQL200

Based on SQL Clearly Explained by Jan Harrington

SQL Programming

Module 1 – Relational Database Background,

Basic Single Table Retrieval Operations


SQL Programming

• Course focus is SQL language

• Widely used for:

– Database administration

– Enterprise application development

– Data driven web sites

• A foundation skill for eBusiness and almost all major business applications that use relational databases

11/25/2011

2


SQL Programming

• A basic knowledge of query systems,

perhaps via MS Access, or some

programming knowledge, is desirable

• We will use “SQL View” almost

exclusively


Relational Database Evolution

• Based on Codd‟s paper

• Early commercial efforts focused on Unix

• First mainframe implementation by IBM -

precursor to today‟s DB2

• First PC implementation in early 80‟s by

Oracle

11/25/2011

3


Relational Database Basics

• Storage

• Databases

• Tables

• Rows

• Columns

• Indexes

• Views

• Cursors

• Application interfaces


Relational Database Table

11/25/2011

4


Constraints

• Database

– Domain

– Uniqueness

– Relationship

Cardinality

• 1 to 1

• 1 to N

• Other Business Rule

– Triggers

– Stored Procedures


Relational Database with constraints

11/25/2011

5


Database Management Systems

Positioning Chart

VLDB

Enterprise

Workgroup

Single user

Spreadsheet

# Users

Cost


System Architecture

AccessMDB

File Server Architecture

Access

11/25/2011

6


System Architecture

OracleDB

Visual Basic App

Client/Server Architecture

Access

SQL


System Architecture

OracleDB

Browser

Web Architecture

WebServer

SQL

11/25/2011

7


Approaching SQL

• Relatively simple

• Two main environments

– Interactive (This course)

– Embedded

• Static (Compiled)

• Dynamic


SQL Standardization

ANSI standardization

– First standard in 1986

– SQL 89

– SQL 92

– SQL 99

• Various vendor extensions

– Microsoft/Sybase: T-SQL

– Oracle: PL/SQL

11/25/2011

8


SQL Conformance

• Entry

• Intermediate

• Advanced

• Most are at least entry level


SQL Statements

• Data Manipulation Language (DML)

• Data Control Language (DCL)

• Data Definition Language (DDL)

• Note: SQL 99 changes these to seven types

11/25/2011

9


SQL DDL

• Data definition language (DDL)

– Create, alter, drop, etc.

– Frequently implemented via various CASE

tools: Visio, Embarcadero, ERWin, etc.

– But very useful for database administration


SQL DCL

• Data Control Language (DDL)

– Grant

– Revoke

– Constraints

11/25/2011

10


SQL DML

• Data Manipulation Language (DML)

– Select

– Insert

– Update

– Delete


SQL Statement Processing

Parse

Validate

Optimize

Access Plan

Execute

11/25/2011

11


Bookstore Sample Database

• Before we continue (note: instructor may have already done this)…

• Load the sample database if you haven‟t already– Use Access import table feature, or

– Run SQL script, or

– Use Access upsizing wizard


Conventions

• In Access character strings are normally

surrounded by double quotes

– “Jones”

• In an enterprise database such as Oracle or SQL

Sever, then single quotes

– „Jones‟

• Be sensitive to the environment of your class in

copying scripts from the PowerPoint slides!

11/25/2011

12


SELECT

Basic Syntax (Projection):

Select <column-list> or <*>

From <table-list>


SELECT

Basic Example (Projection):

select

customer_last_name,

customer_street

from customers

11/25/2011

13


MS Access SQL Query


11/25/2011

14


SQL Server Query


SELECT with Where Clause

Example (Restriction plus Projection):

Select <column-list>

From <table-list>

Where <selection-criteria>;

11/25/2011

15


SELECT with Where

Basic Example (Restriction plus

Projection):

select customer_last_name,

customer_street

from customers

where customer_last_name =

‘Jones’


Select with Where

11/25/2011

16


On Your Own

• Find books written by Mark Twain

• Show title, publisher, year


Complex Predicates

Follow normal boolean logic

Select customer_last_name,

customer_street

From customers

Where (customer_last_name =

‘Jones’ or customer_last_name =

‘Smith’)and customer_state=‘NY’

11/25/2011

17


Select with Complex Where


Complex Where Result

11/25/2011

18


Special Operators

• Can be used in where clause

• LIKE

• IN

• BETWEEN

• IS NULL


Like (“Wild Card Matches”)

• ANSI

• Where

customer_last_name

like “Jo%”

• Like “Jo_”

• Access

• Where

customer_last_name

like “Jo*”

• Like “Jo?”

11/25/2011

19


IN

Select *

From customers

Where customer_last_name in

(‘Rizzo’, ‘Jones’, ‘Garcia’)

The list in parentheses can be replaced by a

subquery. We will study this later.


SQL Where Clause with IN

11/25/2011

20


IS NULL

Select *

From customers

Where customer_street IS NULL

SQL uses three valued logic. Must use IS NULL

to test for unknowns. A null is NOT the same as

blank or empty.


On Your Own

• Find all customers with an address not equal to 4592 Maple Lane

• Was Peter Johnson selected?

• Why or why not?

11/25/2011

21


BETWEEN

Select *

From orders

Where order_date BETWEEN

‘1-jan-99’ and ‘31-dec-99’

Note: date formats vary from product to product.


Where with Between

11/25/2011

22


Removing Duplicates

Select DISTINCT

customer_city

From customers

List once each city in which there are

customers

Removes duplicate rows from result set


Removing Duplicates

11/25/2011

23


Sorting – ORDER BY

DESC will sort in descending order

Basic syntax:

Select <column list>

From <table list>

Where <selection criteria>

Order by <column list> [DESC]


Sorting – ORDER BY

Select *

From customers

Order by customer_state,

customer_city

Example:

List all records sorted by state, city

11/25/2011

24


Sorting Results with Order By


SQL Exercises

• List all books whose publisher name begins with “H” or “T”; sort by title [hint: use LIKE]

• List all customers whose last name ends with “S”; sort by state, city, last name

• Find the order numbers of orders with order dates in 1999; sort by order #. [Hint: use BETWEEN]

• Find the order numbers and order dates of all orders with a “2” in column 2 of the credit card #; sort by order date descending

[end module]

1

Bookstore2 SQL212 Module 2 1

SQL212

SQL Programming

Workshop 2 – Joins, Subqueries, Unions,

Calculations and Grouping


SQL212 Contact Information

P.O. Box 6142

Laguna Niguel, CA 92607

949-489-1472

http://www.d2associates.com

[email protected]

Copyright 2001-2009. All rights reserved.

http://www.d2associates.com/

mailto:[email protected]

2


SQL212

SQL Programming

Part 1 – Joins, Subqueries


Relational Database with constraints (from text)

3


Warning!

• Some slides may show queries using a

table called…

Order_filled

• The current database uses a better name…

Orders

Construct your queries with this

latter table name


Joins

• Inner

• Outer

– Left

– Right

– Full

• Cross

• Self

• Theta

• We will cover the most important; others as time and interest permit

4


Inner Join

• Pairs each row from first table with

corresponding row from second table over

the “join column”

• The result set only contains rows where

there is a match over the join column in

both tables

• Equi-join is the common inner join


Inner Join

Older Syntax:


From <tablelist>

Where <predicate>

Still very commonly used

5

Inner Join Examples

• Show customers and their orders

• Join the customers table to the orders table

where the customer number in each table

matches



Inner Join

Example using older syntax:

SELECT customer_first_name,

customer_street, order_numb,

order_date

from customers, orders

Where customers.customer_numb =

orders.customer_numb

6


Inner Join with Result


Inner Join (New Syntax)

Basic SQL 92 Syntax:


From <table1>

Inner join <table2>

On <join condition>

7


Inner Join

Basic Example:



order_date

from customers

inner join orders

on customers.customer_numb =

orders.customer_numb


Inner Join with Result

8


Inner Join over Multiple columns

• Note that that the join condition can apply

to multiple columns if desired

• Used with composite keys


Inner Join Result in MS Access

9


Inner Join

• In the last example…

– What was the cardinality of the relationship

between customers and orders?

– Which table was the parent?

– What was it‟s primary key?

– In which table did we employ a foreign key

and what was it?


Cross Join

• What happens when you omit a join

expression?

• Get the cartesian product of the tables – all

possible combinations of the two tables

• For large tables this will run a long time!

10

Dual

• Sometimes we want to generate an

expression without actually referring to a

real table.

• A trivial example would show the date.

• Oracle has a 1 row, 1 column built in table

called Dual to handle this.

• Ex: select sysdate from dual;



Cross Join Result Set in MS Access

11


Additional SQL92 Syntax

• Table1 natural join table2 – automatically

uses columns with same name

• Table1 natural join table2 using(<column-

list>)

• Not yet widely available in commercial

implementations

Natural Join


12


Joining More than Two Tables

• Can join several tables in one select

• Try to limit to three or four

• Join order can be important for performance (although optimizers will usually handle this for you)

• Use parentheses to force order of evaluation (also vendor extensions, often called “hints”)


Joining More than Two Tables

• Add orderlines detail to previous queries

SELECT customer_first_name, customer_street,

orders.order_numb, orders.order_date,

orderlines.isbn, orderlines.quantity

FROM customers

INNER JOIN orders ON

customers.customer_numb=orders.customer_numb

INNER JOIN orderlines

on orders.order_numb = orderlines.order_numb

13


Multi-table Join with Results


MS Access Multi-table Join Result Set

14

Own Your Own

• Add the book title to the previous query



Sample Database

• Before we continue (Access classes

only)…

• Create a new employees table

15


Correlation Names (Table Aliases)

• Can abbreviate references to tables

• For example:

Select e.name, j.payrange

From employees as e

Inner join job_information as j

On e.jobcode = j.jobcode;


Self Joins

• Implements a recursive relationship

• Important in various applications

– Parts lists/assemblies

– HR

– Etc.

– Table joined to itself using correlation names

16


Self Joins

SELECT e.*, m.name

FROM employees AS e, employees

AS m

WHERE e.managerid =

m.employeeid;


17


Outer Joins

• Left – selects all rows from the left or first table,

even if no match exists in the other table

– Widely used in commercial practice

– Especially useful for reporting

– Can be slower and interfere with optimizer

• Right – same idea but all rows from right table

• Full – all rows form both tables


Left Outer Join

Basic SQL 92 Syntax:


From <table1>

Left [outer] join <table2>

On <join condition>

18

Outer Join Example

• Show all customers and their orders.

• Include customers with no orders as well.



Left-Join

Basic Example:



order_date

from customers as c

left join orders as o

on c.customer_numb =

o.customer_numb

19



Left Join with Results

20


SQL200

SQL Programming

Part 2– Subqueries, Unions


Subqueries

• One select statement embedded in another.

• Can be paced in select list, from clause or

where clause.

– We will study the latter in this class

• Can be nested multiple levels deep

• Two types:

– Uncorrelated – executes inner query then outer

– Correlated – executes inner query once for each outer

query row

21

Subquery Example

• Show all the orderline information for

orders places in 1999

• Note that orderlines table does not have

order date. Thus must filter on a different

table (orders).



Uncorrelated Subquery

select isbn, quantity

from orderlines ol

where ol.order_numb in

(select o.order_numb from

orders o where order_date

between „1-JAN-99‟ and ‟31-

DEC-99‟)

22


Uncorrelated Subquery with Results


Negative Subquery

• A type of subquery that matches “not

found” conditions

23


Negative Subquery

select isbn, quantity

from orderlines ol

where ol.order_numb not in

(select o.order_numb from

orders o where order_date

between „1-JAN-99‟ and 31-

DEC-99‟)


Negative Subquery with Results

24


Correlated Subquery with Exists

• Inner subquery executed once for each outer row

• Exists will return true or false depending on

whether the result will have any rows or not

• Can be a quick way to test for existence of

records (parent records, say) as used in

application enforcement of referential integrity


Correlated subquery with Exists

SELECT isbn, quantity

FROM orderlines AS ol

WHERE exists

(select * from orders o where

ol.order_numb = o.order_numb

and o.order_date between „1-JAN-

99‟ and „31-DEC-99‟);

This type of query covered in intermediate SQL class

25


Unions

• Combines two tables

• Tables must be union compatible

• Uses:

– Combine current tables with history

– Combine information from tables with no

common join column


Unions

Select <column-list> from

<table1>

Union [ALL]

Select <same-columns> from

<table2>

26

Union Example

• Create a mailing list of customers and

sources

• Use a union of the two tables, making sure

the columns match



Unions

27

Union Results



SQL200

SQL Programming

Part 3 – Calculations, Aggregates

28


Calculated Fields

• Can add a column calculated from others

SELECT order_numb, quantity,

cost_each,

quantity*cost_each as

extension

FROM orderlines


Calculated field in the Result

29



String Manipulation

• Concatenation

• Trim

• Substring

• Upper, Lower

• Etc. (various vendor extensions)

30


Concatenation

• Used for concatenated keys

• Useful to format reports

Basic syntax:

(Oracle, std) Field1 || Field2


Concatenation

select customer_first_name

|| „ „ ||

trim(customer_last_name)

as Name

from customers

31



Date Functions

• Numerous date functions

• Often vendor specific

• Often used:– Take the year of a date

– Take the month of a date

– Add a month (not 30 days)

– Etc.

32


Aggregate Functions

• Count

• Sum

• Min

• Max

• Avg

• Often used in conjunction with grouping


Aggregate Functions

Basic syntax:

Select <function>(<column>)

From <table>

Group by <column-list>

Having <predicate>

Group by all columns to left of one(s)

you want to aggregate

33


Aggregate Functions

SELECT orderlines.order_numb,

Count(*) AS “Number of Order Lines”

, Sum(orderlines.quantity) AS

SumOfquantity, Sum(quantity *

cost_each) AS extension

FROM orderlines

GROUP BY orderlines.order_numb

having count(*) > 1


34


Having vs. Where

• Having and Where clauses are similar but

not the same

• Having removes groups after they are

formed

• Where removes rows before groups are

formed


Exercise

• List all customers and their orders

– Name nicely formatted

– With orders in the year of 1999

– Show total order quantities and amounts

– Only include orders with more than three

order lines

35


Exercise Result

[end module]

Notes


36

Notes


Notes


1

SQL/212

SQL Programming


Workshop 3 – Modifying Data, Managing the Database

SQL212 Contact Information

P.O. Box 6142Laguna Niguel, CA 92607949-489-1472htt // d2 i t


http://[email protected]

Copyright 2001-2009. All rights reserved.

2

SQL212 Module 3

• Part 1 – Modifying Data• Part 2 – Managing Database Structures• Part 3 – Creating Views and Indexes• Part 4 -- Security


SQL/212

SQL Programming


Part 1 – Modifying Data

3

Relational Database with constraints (from text)


Data Modification Statements

• Insert• Insert

• Update

D l t


• Delete

4

Data Modification Statements

• End-user rarely sees theseEnd user rarely sees these statements

• Application developer prepares these statements “behind the scenes” based on forms filled out b


by user

Insert

• Adds new rows to an existing table• Two forms:

– Single Row– Multi-Row


5

Single Row Insert

Basic Syntax:Insert [into] <table-name>

Values (<value-list>)


Single Row Insert

Basic Example:insert into sources(source_numb, source_name, source_street)values(22,'Specialty Books', 'Canal Street')


6

Insert Statement


Sources table after Insert


7

Multi-row Insert

Basic Syntax:

Insert [into] <table-name>

Select <select-statement>


We will do this after creating a new table later in this module

Update

• Updates fields in an existing row

Basic Syntax:

Update <table-name>

Set <field1> = new value <field2> = new


Set <field1> new value, <field2> new value,…

Where <selection-criteria>

8

Update

• Increase Ingram prices by 10%

Example:

Update books

Set retail price = retail price


Set retail_price retail_price *1.10

Where source_numb = 1

Ingram Book Prices before Update


9

Ingram Book Prices after Update


Delete

• Deletes one or more rows

Basic Syntax:

Delete from <table-name>


Where <selection-criteria>

10

Delete

Example: delete the source we added

Delete from sources

h b 22


Where source_numb = 22

Delete


11

Sources table after Delete


Delete and Referential Integrity• Can affect referential integrity when deleting a

“parent” rowparent row• Can do following with child…

– Cascade: delete the child row– Set null: set the child’s foreign key null– Set default: as above but to default value– No action: don’t allow delete of parent row

• Referential integrity can be established when


• Referential integrity can be established when creating or modifying table structures which we will look at later in the class

12

SQL/212

SQL Programming


Part 2– Managing Database Structures

Schemas

• Logical view of a database; sort of a “sub-database” – we will not cover these in this module…– Catalogs– Clusters– Domains (somewhat like a user defined datatype)


• These topics are highly dependent upon the vendor DBMS and installation practices– In Oracle you are logged in to your schema

13

Tables

• Two types• Two types– Base tables– Temporary tables

• Local (or module scope)• Global (session scope)


• We will create base tables in this class

Creating Tables

• Use create statement• Specify:

– Columns with data types and column constraints

– Table constraints• Foreign key references


• Foreign key references• Primary key designation

14

Data Types

• Int – integers or whole numbers– Ex: how_many int

• Char – fixed length fields– Ex: state char(2)

• Varchar/Varchar2 – variable length fields– Ex: address varchar2(35)

• Money money field


• Money – money field• Date/Datetime – date and time • And many others – see documentation or Help

Create Table

Basic syntax:

Create table <table-name>

<column1> <datatype> <constraints>

,.. <column1> <datatype> <constraints>


…

<table constraints>Note: often preceded by a drop

15

Temporary Tables

Basic syntax:

Create [global] temporary table <table-name>

<rest of statement as for normal create>


Note: SQL Server uses a different syntax. Just put a #in front of the table name as in #mytable. Access doesn’t have true temporary tables.

Column Constraints

• Primary key• Not NULL• CHECK clause• Default• Unique


q

16

Table Constraints

• Primary Key• Foreign Key• Compare fields against each other. I.e.

ship_date >= order_date


But first – the Drop Statement

• Deletes a database “object”– Drop table <table-name>– Drop view <view-name>– Drop index <index-name>– Drop domain <domain-name>


17

Create Table

Example 1: Create a summary tableCreate table summary(

isbn varchar2(20) primary key,

How_many int check (how_many >= 0),

Constraint isbn_fk


Foreign key (isbn) referencesbooks(isbn)

)

Create Summary Table


18

Constraints on Summary Table


Multi-row Insert

Basic Syntax:

Insert [into] <table-name>


Select <select-statement>

19

Multi-row Insert

Basic Example: (store # times each book ordered)

Insert into summary(isbn, how_many)

S l t i b t(*)


Select isbn, count(*)

From orderlines

Group by isbn;

Multi-row Insert


20

After multi-row insert in MS Access


SQL/212

SQL Programming


Part 3 – Creating Views and Indexes, Modifying Structures

21

Views

• Think of a view as a named query wherein the definition is stored in the database

• Can be read like a table• Some are updateable


Views

Basic syntax:

Create view <view-name> (<column-list>)

As

<select statement>


22

Creating a View

• Example: show inventory for each book


Using Views

• Can be used like a table subject to various limitations– Cannot insert into grouped queries, etc.– Etc.

• Sample syntax:l l l


select column-listfrom employee_view

23

Using a View


Indexes

• Used to speed searches, joins, etc.• Placed on:

– primary and foreign keys– Secondary keys

• In commercial practice often managed by


DBA’s for large databases

24

Indexes

Basic syntax:y

Create [unique] index <index-name>

On <table-name> (field-name> [desc])


Note: can place index on a composite key; ex: state and city

Indexes

• Add an index on state to speed searches

Basic example:

t i d t t i

and reporting


create index state_inx

on customers(customer_state)

25

After indexing on customer_state


State_inx in Oracle


26

Modifying a Table Design

• Applies to tables• Use ALTER statement

– Add columns– Delete columns– Rename columns


– Add column constraints– Add table constraints

Modifying a Table Design

Basic syntax:y

Alter <table-name>

Add <field-name>,

Add <table-constraint>,

M dif fi ld


Modify <field-name>

Etc.

27

Modify a Table Design

l dd h b fi ldExample: add a phone number field

alter table publishers

add phone char(12);


After alter publishers table


28

SQL/212

SQL Programming


Part 4 – Security

Security

• Important DBA function– Beyond scope of this course– Typically controlled through Enterprise

Manager or Studio GUI’s• In commercial practice application security

frequently controlled via own login and a


frequently controlled via own login and a “users” table or similar

29

Security

• Specifics can vary by product• Access: workgroup administrator• SQL Server: users, roles• Oracle: users, roles


SQL Security Statements

• Grant• Revoke• Deny


30

Grant

Syntax:

Grant <access-right> [with grant option]

On <object> to <user>


Note: by default only tables owners and admins can access a table. Others must be granted the relevant rights.

Access Rights

• Select• Update• Insert• Delete• References


• All privileges

31

Grant

Example: Give user ddurso the permission to update the employees table.

Grant update


On employees to ddurso

Revoke

• Revokes the rights• Syntax similar to grant


[end module]

32

Notes


Notes


Accelerated Computer Training for Working Professionals

Orange Coast Database Associates Course (800)355-9855 or http://ocdatabases.itgo.com

Orange Coast

Database Associates

Specializing in Microsoft Office,

Access, SQL, and related technologies Computer Training, Programming & Consulting

32422 Alipaz St., Suite A-15

San Juan Capistrano, CA

(800)355-9855 (Toll Free) | (949)489-1472 (Direct) | (949)485-6284 (Fax)

http://www.dhdursoassociates.com | [email protected]

Accelerated Computer Training

SQL212 Oracle SQL Manual

Technology

sql language

sql focus

approaching sql

basic sql session

tsql oracle

oracle sql developer

prior knowledge of sql

sql statement pr