?????????????????????????????????????????????????????????????????????????á?????????????????????????е??????????????????????????á????????????????漰?????????DELETE??UPDATE????????????????????????Щ???????????????????????????????????????2.8???????????????????????

??????????漰??????????DELETE??UPDATE??????????????????ж???????????????????????????????????????е???????????????????????????????t???id?????100????????????????????д????????????

????DELETE FROM t WHERE id > 100;

??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????t?????id?????????????????t2????????????????????????

???????д????漰?????????DELETE????????????漰?????????FROM?????????г????????????????й??????У??????????????????????????д??WHERE???????????????佫???????t1?????id?????????????????t2????????????????????

????DELETE t1 FROM t1 INNER JOIN t2 ON t1.id = t2.id;

????????????????е??????????????????????п?????????????????????????????????????????

????DELETE??????????????????????????????????????????С?????????????????????id????????????ж???????????DELETE?????????д?????????????????

????DELETE t1?? t2 FROM t1 INNER JOIN t2 ON t1.id = t2.id;

????????????????????????????У????????????漰?????????DELETE???????????????????SELECT???????κ????????????????????????????д????????????????????????е?SELECT?????·??????????????????????LEFT JOIN???????RIGHT JOIN?????????????????????t1??????????t2????????????????????????????д??????????????SELECT???

????SELECT t1.* FROM t1 LEFT JOIN t2 ON t1.id = t2.id WHERE t2.id IS NULL;

????????????????t1??????????Щ?????е?DELETE???????????LEFT JOIN??????

????DELETE t1 FROM t1 LEFT JOIN t2 ON t1.id = t2.id WHERE t2.id IS NULL;

????MySQL???????????漰?????????DELETE????????????????FROM??????г???????????й??????е?????????????USING???????????й?????????????Щ?????????????????????????漰?????????DELETE????????????????д???????????????

????DELETE FROM t1 USING t1 INNER JOIN t2 ON t1.id = t2.id; 
????DELETE FROM t1?? t2 USING t1 INNER JOIN t2 ON t1.id = t2.id; 
????DELETE FROM t1 USING t1 LEFT JOIN t2 ON t1.id = t2.id WHERE t2.id IS NULL; 

??????д?漰?????????UPDATE??????????????д?漰?????????DELETE?????????????????г????漰???????????????????????????????????е???????б?????????????????????????????2008??9??23??????????????????????????????д??????????????????????????????д????????????????λ???????????????????????????漰?????????UPDATE??????????????????

????UPDATE score?? grade_event SET scorescore.score = score.score + 1 
????WHERE score.event_id = grade_event.event_id 
????AND grade_event.date ='2008-09-23' AND grade_event.category = 'Q'; 

???????嵽?????????????????????????????????????2????????????????

????UPDATE score SET scorescore = score + 1  
????WHERE event_id = (SELECT event_id FROM grade_event  
????WHERE date = '2008-09-23' AND category = 'Q'); 

?????????????????2?????????????????????????????????????????????????????????????????????????????????????????Щ?????У???????????????????????????????????????????????????佫???????????t1.a?????t2.a??????????????????????????????id?????????

????UPDATE t1?? t2 SET t2.a = t1.a WHERE t2.id = t1.id;

??????????InnoDB???????ж?????????????2?????????????????????????????????????????佨?????????????????????ON DELETE CASCADE??ON UPDATE CASCADE?????????