VARIABLE DECLERATIONS AND CONSTANT DECLERATIONS

VARIABLE DECLERATIONS

Variables can be declared in declarative section of the block;

Ex:

DECLARE

      a number;

      b number := 5;

      c number default 6;

CONSTANT DECLERATIONS

To declare a constant, you include the CONSTANT keyword, and you must supply a default value.

Ex:

DECLARE

      b constant number := 5;

      c constant number default 6;

NOT NULL CLAUSE

You can also specify that the variable must be not null.

Ex:

DECLARE

      b constant number not null:= 5;

      c number not null default 6;