DELIMITER $$
 
USE `mysql`$$
 
DROP PROCEDURE IF EXISTS `mysp_rename_proc`$$
 
CREATE DEFINER=`root`@`%` PROCEDURE `mysp_rename_proc`(IN p_proc_name VARCHAR(64), IN p_new_name VARCHAR(64), IN p_db VARCHAR(64))
    MODIFIES SQL DATA
    SQL SECURITY INVOKER
    COMMENT 'Use to rename stored procedures.'
BEGIN
    proc: BEGIN
	# A few tests to see if the input is sensible
	IF CHARACTER_LENGTH(IFNULL(p_proc_name, '')) = 0 OR CHARACTER_LENGTH(IFNULL(p_new_name, '')) = 0
		OR CHARACTER_LENGTH(IFNULL(p_db, '')) = 0 THEN
	BEGIN
		SELECT 'Error: One of more of the input parameters is zero in length.' AS Error;
		LEAVE proc; 
	END;
	ELSEIF (SELECT COUNT(*)
		 FROM mysql.proc
		 WHERE `name` = p_proc_name
		 AND `type` = 'PROCEDURE'
		 AND db = p_db) = 0 THEN
	BEGIN
		SELECT 'Error: The procedure specified in p_proc_name does not exist in this database.' AS Error;
		LEAVE proc;
	END;
	ELSEIF (SELECT COUNT(*)
		 FROM mysql.proc
		 WHERE `name` = p_new_name
		 AND `type` = 'PROCEDURE'
		 AND db = p_db) = 1 THEN
	BEGIN
		SELECT 'Error: Unable to rename the procedure specified in p_proc_name as it already exists in this database.' AS Error;
		LEAVE proc;
	END;
	END IF;
 
	# Rename the proc
	UPDATE `mysql`.`proc`
	SET `name` = p_new_name,
	specific_name = p_new_name
	WHERE db = p_db 
	AND `name` = p_proc_name
	AND `type` = 'PROCEDURE';
 
	# Update any associated privileges
	UPDATE `mysql`.`procs_priv`
	SET Routine_name = p_new_name
	WHERE db = p_db 
	AND Routine_name = p_proc_name
	AND Routine_type = 'PROCEDURE';
 
	# Check update rowcount to see if privileges need to be flushed
	IF(SELECT ROW_COUNT()) > 0 THEN
	BEGIN
		FLUSH PRIVILEGES;
	END;
	END IF;
 
    END proc;
    END$$
 
DELIMITER ;

CALL mysp_rename_proc('usp_proc', 'usp_new_proc_name', 'database_proc_exists_in');