By yusijia

Updated:

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# 注意使用new和old
# 因为是AFTER INSERT，是插入，所以用new代替新插入的那条信息
CREATE TRIGGER trig_book AFTER INSERT 
     ON t_book FOR EACH ROW
        UPDATE t_bookType SET bookNum=bookNum+1 WHERE new.bookTypeId=t_booktype.id;
        
        
INSERT INTO t_book VALUES(NULL,'java好',100,'ke',1);


# 下面一次性要执行三条操作语句，有三个分号，所以要用DELIMITER
# 因为是AFTER DELETE 是删除，所以下面用old代替要删除的那条信息

DELIMITER |
CREATE TRIGGER trig_book2 AFTER DELETE 
    ON t_book FOR EACH ROW
    BEGIN
       UPDATE t_bookType SET bookNum=bookNum-1 WHERE old.bookTypeId=t_booktype.id;
       INSERT INTO t_log VALUES(NULL,NOW(),'在book表里删除了一条数据');
       DELETE FROM t_test WHERE old.bookTypeId=t_test.id;
    END 
|
DELIMITER ;

DELETE FROM t_book WHERE id=5;

SHOW TRIGGERS;

DROP TRIGGER trig_book2 ;
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