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Oracle SQL and PLSQL

SQL stands for Structured Query Language and it is generally referred to as

SEQUEL and it is a Nonprocedural language as compared to the procedural or

third generation languages such as COBOL and C. It was developed by IBM in the

year 1970s.The American National Standards Institute published its first SQLstandard in the year 1986 and secondly in the year 1989.ANSI released updates in

the 1992 known as SQL92 and SQL2 and again in the year 1999 known as SQL 99

and SQL3.Every Time ANSI added new features and incorporated new commands

and capabilities in to the language.

SQL is simple ,yet powerful ,language used to create, access, manipulate data and

structure in the database.

SQL Statement Categories:

DDL- Data Definition Language

DDL is used to define alter and drop database objects and their privileges. DDL

statements will implicitly perform a commit.

DDL Statements:

Create: it is used to create objects(tables ,view) in the database.

Alter: it is used to alter the structure of the database objects.

Drop: delete database objects(it will invalidate the dependent objects, it also drops

indexes, triggers and referential integrity constraints).

Truncate: remove all records from a table, including all the spaces allocated for the

records are removed(it is first as compared to delete and does not generate undo

information as Delete does.it performs implicit commit as it is a DDL.

DML: Data Manipulation Language:

DML is used to access, create and modify or delete data in the structures in the

database.

DML Statements:

Select: select data from the database.

Insert: it is used to insert data into table.

Update: It is used to update existing data with in a table.

Delete: it removes rows from the table.

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DCL: Data Control Language

DCL Statements:

Commit: it will end current transaction making the changes permanent and visibleto all the users.

Savepoint: it will identify the point(named SAVEPOINT) in a transaction to which you

can later rollback.

Rollback: it will undo all the changes made by the current transactions.

Set-Transaction: it is used to define the properties of a transaction.

SQL syntax:

SQL Select statement:

SELECT* column name FROM table name

Example:

Select salary from emp;

SQL where:

SELECT column name

FROM table name

WHERE condition

Example:

Select salary from emp;

Where salary >2000

SQL Distinct:

SELECT DISTINCT column name

FROM table name

Example:

Select DISTINCT name from emp;

SQL And/or

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SELECT column name

FROM table name

WHERE condition

{[ANDOR]condition}+

Example:

SELECT salary

FROM emp

WHERE salary >1000

OR (salary 275)

SQL Between

SELECT column name

FROM table name

WHERE column name BETWEEN value1 AND value2

Example:

SELECT*

FROM emp

WHERE Date BETWEEN Jan-01-1999 AND jan-15-1999

SQL in

SELECT column name

FROM table name

WHERE column name IN(value1,value2)

Example:

SELECT*

FROM emp

WHERE last_name IN (sharma, dhall)

SQL like

SELECT column name

FROM table name

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WHERE column name LIKE{PATTERN}

Example:

SELECT*

FROM table name

[WHERE condition]

ORDER BY column name[ASC,DESC]

Example:

SELECT name, salary

FROM emp

ORDER BY name DESC

SQL Count

SELECT COUNT( column name)

FROM table name

Example:

SELECT COUNT( salary)

FROM emp

SELECT * FROM Table;

In the above query SELECT and FROM are SQL keywords,* is a wildcard which means all

columns