Define a Variable

User/Session variables

Use @ as prefix to declare a new user variable. Scope of user variable are outside the PROCEDURE or FUNCTION.

sql

set @variable_name = [value]

To pass a variable to a PROCEDURE or FUNCTION, must also prefixed with @.

Use DECLARE keyword to declare a local variable. Scope of local variable are inside the PROCEDURE or FUNCTION.

For all types in SQL, the implicit DEFAULT value is NULL. Try explicitly assign default value using DEFAULT.

sql

DECLARE variable_name [type] DEFAULT [default_value];