mysql 嵌套查询 MySQL嵌套查询

乐乐今天给分享mysql 嵌套查询的知识，其中也会对MySQL嵌套查询进行解释，希望能解决你的问题，请看下面的文章阅读吧！

1、找出工资大于Mark的员工名字和工资count()不可以哦，这不是MYSQL的问题，数据库都有这个规定：不允许UPDATE的子查询里面有被UPDATE的那个表。

2、我一般采取两种方法，一是利用SQL文本：SELECT CONCAT("UPDATE RES_OBJECT SET MULTISELECT_ID=",B.MULTISELECT_ID,"WHERE RES_ID=",A.RES_ID,";")INTO OUTFILE ABC.SQLFROM RES_OBJECT A,RES_OBJECwhile($row2 = $dosql->GetArray()){T BAND (RES_OBJECT.MULTISELECT_ID IS NULL OR RES_OBJECT.MULTISELECT_ID=0);SOURCE ABC.SQL;另外一种方法是利用临时表：SELECT B.MULTISELECT_ID,A.RES_IDFROM RES_OBJECT A,RES_OBJECT BAND (RES_OBJECT.MULTISELECT_ID IS NULL OR RES_OBJECT.MULTISELECT_ID=0)INTO TEMP TABLE TMP;UPDATE RES_OBJECT SET MULTISELECT_ID=(SELECT MULTISELECT_ID FROM TMP WHERE TMP.RES_ID=RES_OBJECT.RES_ID)WHERE EXISTS(SELECT MULTISELECT_ID FROM TMP WHERE TMP.RES_ID=RES_OBJECT.RES_ID);。

本文到这结束，希望上面文章对大家有所帮助。