FW：Mysql 触发器

1、创建触发器: 
语法: 

CREATE TRIGGER trigger_name trigger_time trigger_event ON tbl_name
FOR EACH ROW
BEGIN
 trigger_stmt
END；

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： 

DROP TRIGGER t_wiley_hotelComment_bu;
delimiter //
CREATE TRIGGER t_wiley_hotelComment_bu BEFORE UPDATE ON hotel_comment
FOR EACH ROW
BEGIN
    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 ;

说明：delimiter 改变语句结束符