Declaring and Assigning Values to Variables and Constants

One significant advantage that PL/SQL has over SQL is that PL/SQL lets you declare and use variables and constants.

A variable or constant declared in a package specification can be used by any program that has access to the package. A variable or constant declared in a package body or subprogram is local to that package or subprogram.

A variable holds a value of a particular data type. Your program can change the value at run time. A constant holds a value that cannot be changed.

A variable or constant can have any PL/SQL data type. When declaring a variable, you can assign it an initial value; if you do not, its initial value is NULL. When declaring a constant, you must assign it an initial value. To assign an initial value to a variable or constant, use the assignment operator (:=).

This section contains:

• Tutorial: Declaring Variables and Constants in a Subprogram

• Ensuring that Variables, Constants, and Parameters Have Correct Data Types

• Tutorial: Changing Declarations to Use the %TYPE Attribute

• Assigning Values to Variables