Introduction to PLSQL

PLSQL is the combination of SQL statements. To increase the capabilities of SQL PLSQL is introduced. Full form of PLSQL is 'Procedural Structured query language'. 

* PL/SQL programs are divided and written in logical blocks of code. Each block consists of three sub-parts

- Declarations

- Executable Commands

- Exception Handling

* Following is the basic structure of a PL/SQL block

DECLARE 

<declarations section> 

BEGIN 

<executable command(s)>

EXCEPTION 

<exception handling> 

END;

* The PL/SQL single-line comments start with the delimiter -- (double hyphen) and multi-line comments are enclosed by /* and */.

 Example : 

    DECLARE 

   -- variable declaration 

   message  varchar2(20):= 'Hello, World!'; 

   BEGIN 

   /* 

   *  PL/SQL executable statement(s) 

   */ 

   dbms_output.put_line(message); 

   END; 

   /  

* A PL/SQL unit is any one of the following −

 PL/SQL block

 Function

 Package

 Package body

 Procedure

 Trigger

 Type

 Type body