DELETE刪除多表數(shù)據(jù)，怎樣才能同時(shí)刪除多個(gè)關(guān)聯(lián)表的數(shù)據(jù)呢？這里做了深入的解釋：
1 delete from t1 where 條件
2 delete t1 from t1 where 條件
3 delete t1 from t1,t2 where 條件
4 delete t1,t2 from t1,t2 where 條件
前 3者是可行的，第4者不可行。
也就是簡單用delete語句無法進(jìn)行多表刪除數(shù)據(jù)操作，不過可以建立級聯(lián)刪除，在兩個(gè)表之間建立級聯(lián)刪除關(guān)系，則可以實(shí)現(xiàn)刪除一個(gè)表的數(shù)據(jù)時(shí)，同時(shí)刪除另一個(gè)表中相關(guān)的數(shù)據(jù)。
1、從數(shù)據(jù)表t1中把那些id值在數(shù)據(jù)表t2里有匹配的記錄全刪除掉1 DELETE t1 FROM t1,t2 WHERE t1.id=t2.id 或 DELETE FROM t1 USING t1,t2 WHERE t1.id=t2.id
2、從數(shù)據(jù)表t1里在數(shù)據(jù)表t2里沒有匹配的記錄查找出來并刪除掉1 DELETE t1 FROM t1 LEFT JOIN T2 ON t1.id=t2.id WHERE t2.id IS NULL 或 DELETE FROM t1,USING t1 LEFT JOIN T2 ON t1.id=t2.id WHERE t2.id IS NULL
3、 從兩個(gè)表中找出相同記錄的數(shù)據(jù)并把兩個(gè)表中的數(shù)據(jù)都刪除掉1 DELETE t1,t2 from t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t1.id=25
注意此處的delete t1,t2 from 中的t1,t2不能是別名
如：1 delete t1,t2 from table_name as t1 left join table2_name as t2 on t1.id=t2.id where table_name.id=25
在數(shù)據(jù)里面執(zhí)行是錯誤的（MYSQL 版本不小于5.0在5.0中是可以的）
上述語句改 寫成1 delete table_name,table2_name from table_name as t1 left join table2_name as t2 on t1.id=t2.id where table_name.id=25
在數(shù)據(jù)里面執(zhí)行是錯誤的（MYSQL 版本小于5.0在5.0中是可以的）