SQL嵌套查询总结

IT也有一段时间了,刚开始的时候``````的困难主要是在编程语言上,数组,逻辑,算法,...这些都过来了之后,困难就上升到数据库设计上了.以及数据逻辑.一个优秀的系统,会集成优秀的程序和优秀的数据库设计.要做到这点得有足够的经验.这是我写的一个结合UINON的嵌套查询.将五个方面的报表放到一个临时表里,再从临时表里,将所要的数据查询出来.

复制代码 代码如下:

$sql="SELECT type , sum( yjsl ) as yjsl , sum( yysl ) as yysl, sum( jyrs ) as jyrs, sum( jycs ) as jycsFROM (SELECT c.mc ASTYPE , count( d.lsh ) AS yjsl, 0 AS yysl, 0 AS jyrs, 0 AS jycsFROM sys_dzxxb AS b, sys_jcb AS c, sys_dzyjb AS dWHERE b.bm = c.lshAND d.dzlsh = b.lshGROUP BY c.mcUNION SELECT c.mc ASTYPE , 0 AS yjsl, count( e.lsh ) AS yysl, 0 AS jyrs, 0 AS jycsFROM sys_dzxxb AS b, sys_jcb AS c, sys_dzyy AS eWHERE b.bm = c.lshAND e.dzlsh = b.lshGROUP BY c.mcUNION SELECT c.mc ASTYPE , 0 AS yjsl, 0 AS yysl, count( DISTINCT e.dzlsh ) AS jyrs, 0 AS jycsFROM sys_dzxxb AS b, sys_jcb AS c, sys_ltxxb AS eWHERE b.bm = c.lshAND e.dzlsh = b.lshGROUP BY c.mcUNION SELECT c.mc ASTYPE , 0 AS yjsl, 0 AS yysl, 0 AS jyrs, count( DISTINCT e.lsh ) AS jycsFROM sys_dzxxb AS b, sys_jcb AS c, sys_ltxxb AS eWHERE b.bm = c.lshAND e.dzlsh = b.lshGROUP BY c.mc) AS temptableGROUP BY TYPE ";

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