ALTER PROCEDURE syntax
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The syntax for ALTER PROCEDURE is similar to CREATE PROCEDURE as shown in the following syntax:
ALTER PROCEDURE name
[(var data_type [, var data_type …])]
[RETURNS (var data_type [, var data_type …])]
AS
procedure_body;
The procedure <name> must be the name of an existing procedure. The arguments of the ALTER PROCEDURE statement are the same as those for CREATE PROCEDURE (see Arguments of the CREATE PROCEDURE statement on the page CREATE PROCEDURE syntax).