摘要： 1: 效率高， 连接，update 后跟别名update a set a.Field1= b.Field1fromTable1 aleft joinTable2 b on a.SID=b.IDwhere b.Codelike 'm%'效率高2: 子查询，update后跟表名update Table1set Field1= (select Field1 from Table2where Table2... 阅读全文