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 1、创建触发器:
语法: 

Java代码

1. CREATE TRIGGER trigger_name trigger_time trigger_event ON tbl_name  
2. FOR EACH ROW   
3. BEGIN  
4.  trigger_stmt  
5. END；  

CREATE TRIGGER trigger_name trigger_time trigger_event ON tbl_nameFOR EACH ROW BEGIN trigger_stmtEND；

大写的为关键字
trigger_name:触发器的名字，我常用的命名规则t_name_tableName_(b|a)(i|u|d),t:触发器标识，name:英文名，tableName:表名，b(BEFORE):标识是触发事件之前，a(AFTER):标识触发事件之后,i(insert):标识insert事件，u(update):标识update事件，d(delete):标识delete事件;
trigger_time:触发时间(BEFORE或AFTER)
trigger_event:事件名(insert或update或delete)
tbl_name:表名(必须是永久性表)
trigger_stmt：执行语句(可以是复合语名)，使用别名OLD和NEW，能够引用与触发程序相关的表中的列。
2、删除解发器
语法：
DROP TRIGGER [schema_name.]trigger_name；
注意：以上操作均需SUPER权限
示例：

Java代码

1. DROP TRIGGER t_wiley_hotelComment_bu;  
2. delimiter //  
3. CREATE TRIGGER t_wiley_hotelComment_bu BEFORE UPDATE ON hotel_comment  
4. FOR EACH ROW  
5. BEGIN  
6.     IF OLD.ispass=0 && NEW.ispass=1 THEN  
7.        UPDATE hotel_info SET sumcomment=sumcomment+1,sumconsume=sumconsume+NEW.consume,sumservice=sumservice+NEW.service, sumroom=sumroom+NEW.room,sumentiron=sumentiron+NEW.entironment,total=total+(NEW.service+NEW.room+NEW.entironment) WHERE hotel_id=NEW.hotel_id;  
8.   ELSEIF OLD.ispass=1 && NEW.ispass=0 THEN  
9.      UPDATE hotel_info SET sumcomment=sumcomment-1,sumconsume=sumconsume-NEW.consume,sumservice=sumservice-NEW.service, sumroom=sumroom-NEW.room,sumentiron=sumentiron-NEW.entironment,total=total-(NEW.service+NEW.room+NEW.entironment) WHERE hotel_id=NEW.hotel_id;  
10.   END IF;  
11. END;//  
12. delimiter ;  

DROP TRIGGER t_wiley_hotelComment_bu;delimiter //CREATE TRIGGER t_wiley_hotelComment_bu BEFORE UPDATE ON hotel_commentFOR EACH ROWBEGIN    IF OLD.ispass=0 && NEW.ispass=1 THEN       UPDATE hotel_info SET sumcomment=sumcomment+1,sumconsume=sumconsume+NEW.consume,sumservice=sumservice+NEW.service, sumroom=sumroom+NEW.room,sumentiron=sumentiron+NEW.entironment,total=total+(NEW.service+NEW.room+NEW.entironment) WHERE hotel_id=NEW.hotel_id;  ELSEIF OLD.ispass=1 && NEW.ispass=0 THEN     UPDATE hotel_info SET sumcomment=sumcomment-1,sumconsume=sumconsume-NEW.consume,sumservice=sumservice-NEW.service, sumroom=sumroom-NEW.room,sumentiron=sumentiron-NEW.entironment,total=total-(NEW.service+NEW.room+NEW.entironment) WHERE hotel_id=NEW.hotel_id;  END IF;END;//delimiter ;

触发器使用
 delimiter可以改变语句结束符

delimiter //
CREATE TRIGGER `trigger_target_update_last_track` AFTER UPDATE ON `target` FOR EACH ROW begin
    set @oldmac = (select concat(old.device, ':', old.address));
    set @newmac = (select concat(new.device, ':', new.address));
    update last_track set mac=@newmac where mac = @oldmac;
end; //