MySQL Insert되는 데이터 특정 컬럼 값 update 트리거

# MySQL Insert되는 데이터 특정 컬럼 값 update 트리거

CREATE TRIGGER UPDATE_FILES_UNCD_TRIG BEFORE INSERT ON RD_FILES 
	FOR EACH ROW 
	BEGIN 
		SET NEW.FILE_UNCD = (SELECT CONCAT('S0000F', CAST(LPAD((CAST(SUBSTRING(MAX(FILE_UNCD), 7) AS UNSIGNED) + 1), 5, '0') AS char))
									FROM RD_FILES);
	END;