触发器

三种出发器： insert 触发器， delete触发器， update触发器

eg：

CREATE TABLE tableA

(id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,

tablename VARCHAR(20));

CREATE TABLE tableB

(id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,

tablename VARCHAR(20));

CREATE TRIGGER t_insert_tableA

AFTER INSERT ON tableA

FOR EACH ROW

INSERT INTO tableB(tablename) VALUES(new.tablename);

INSERT INTO tableA VALUES(1,'aa');

CREATE TRIGGER t_inbefore_tableA

BEFORE INSERT ON tableA

FOR EACH ROW

INSERT INTO tableB(tablename) VALUES(new.tablename);

INSERT INTO tableA VALUES(2, 'bb');

CREATE TRIGGER t_del_tableA

BEFORE DELETE ON tableA

FOR EACH ROW

DELETE FROM tableB WHERE id=old.id;

DELETE FROM tableA WHERE id=1;

DELIMITER //

CREATE TRIGGER t_update_tableA

BEFORE UPDATE ON tableA

FOR EACH ROW

BEGIN

SET new.tablename = UPPER(new.tablename);

END //

DELIMITER ;

UPDATE tableA SET tablename='tian' WHERE id=2;