Redeclaration or Redefinition

If you define the same variable twice in the same statement block, you receive an error. You can redefine a variable within a nested block, in which case it temporarily hides the outer declaration. This example produces an error:

CREATE PROCEDURE example1() 
   DEFINE n INT; DEFINE j INT;
   DEFINE n CHAR (1);    -- redefinition produces an error

Redeclaration is valid in the following example. Within the nested statement block, n is a character variable. Outside the block, n is an integer variable.

CREATE PROCEDURE example2() 
   DEFINE n INT; DEFINE j INT;
   ...
   BEGIN
   DEFINE n CHAR (1);    -- character n masks global integer variable
   ...
END;