CREATE DEFINER = 'mysql'@'%'
PROCEDURE my_bd.procedure_test(OUT Param1 DECIMAL(12,2))
BEGIN
PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) INTO Param1';
SET @a = 3;
SET @b = 4;
EXECUTE stmt1 USING @a, @b;
DEALLOCATE PREPARE stmt1;
END

CREATE DEFINER = 'mysql'@'%'
PROCEDURE my_bd.procedure_test(OUT Param1 DECIMAL(12,2))
BEGIN
DECLARE result decimal(12,2);
PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) as sqrt into @result';
SET @a = 3;
SET @b = 4;
EXECUTE stmt1 USING @a, @b;
DEALLOCATE PREPARE stmt1;
SELECT @result INTO Param1;
END