Use of Variables in PL/pgSQL

Variables can be used for :

• Temporary storage of data
• Manipulation of stored values
• Reusability

Handling Variables in PL/pgSQL

Variables are :

• Declared and initialized in the declarative section
• Used and assigned new values in the executable section
• Passed as parameters to PL/pgSQL subprograms
• Used to hold the output of a PL/pgSQL subprogram

         DECLARE
         emp_hiredate DATE;
         emp_deptno NUMERIC := 10;
         location VARCHAR(13) := 'Atlanta';

Guidelines for Declaring PL/pgSQL Variables

• Avoid using column names as identifiers.
• Use the NOT NULL constraint when the variable must hold a value.

PL/pgSQL

PL/pgSQL Block Structure

• DECLARE (Optional) 
• Variables, 
• cursors,
• BEGIN (Mandatory) 
• SQL statements 
• PLPGSQL statements
• EXCEPTION (Optional) 
• Actions to perform when errors occur
• END; (Mandatory)

• All key words and identifiers can be written in mixed upper and lower case. Identifiers are implicitly converted to lowercase unless doublequoted.
• There are two types of comments in PL/pgSQL.
• -- starts a comment that extends to the end of the line.
• /* multi-line comments */