Declaring variables : Introduction « PL SQL Programming « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. PL SQL Programming
3. Introduction

In PL/SQL, variables must be included in the declaration block before they can be used.

There are a number of ways to declare a variable.

The most common way is by using a direct declaration, as shown here:

declare
    variable_name [constant] DATATYPE [DEFAULT value |DEFAULT NULL];
begin
    ...

The keyword constant means that the variable's value can't be changed in the body of the program.

If you declare a variable as a constant, you must assign a default value to it by using the optional DEFAULT value clause.

The following shows an example of correct declarations of variables:

SQL> declare
  2      v_sal   NUMBER;
  3      v_name  VARCHAR2(10) DEFAULT 'KING';
  4      v_start_dt DATE := SYSDATE; -- same as DEFAULT SYSDATE
  5  begin
  6      NULL;
  7  end;
  8  /

PL/SQL procedure successfully completed.

SQL>