摘要：
对于union的sql语句 尽量做到同类归并例如：select ..from A,B,C,D1where conditon on D1and (joins and other conditons）unionselect ..from A,B,C,D2where condtion on D2and (joins and other conditons)为提高效率select ..fromA,B,C,(select .. from D1 where conditon on D1unionselect .. from D2 where condition on D2)Dwhere joins and 阅读全文
posted @ 2011-02-23 23:48
张御扬
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