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SQL嵌套查询总结

  • 时间:2021-04-05 05:18 编辑: 来源: 阅读:
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摘要: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. 
[u]复制代码[/u] 代码如下:
$sql="SELECT type , sum( yjsl ) as yjsl , sum( yysl ) as yysl, sum( jyrs ) as jyrs, sum( jycs ) as jycs FROM ( SELECT c.mc AS TYPE , count( d.lsh ) AS yjsl, 0 AS yysl, 0 AS jyrs, 0 AS jycs FROM sys_dzxxb AS b, sys_jcb AS c, sys_dzyjb AS d WHERE b.bm = c.lsh AND d.dzlsh = b.lsh GROUP BY c.mc UNION SELECT c.mc AS TYPE , 0 AS yjsl, count( e.lsh ) AS yysl, 0 AS jyrs, 0 AS jycs FROM sys_dzxxb AS b, sys_jcb AS c, sys_dzyy AS e WHERE b.bm = c.lsh AND e.dzlsh = b.lsh GROUP BY c.mc UNION SELECT c.mc AS TYPE , 0 AS yjsl, 0 AS yysl, count( DISTINCT e.dzlsh ) AS jyrs, 0 AS jycs FROM sys_dzxxb AS b, sys_jcb AS c, sys_ltxxb AS e WHERE b.bm = c.lsh AND e.dzlsh = b.lsh GROUP BY c.mc UNION SELECT c.mc AS TYPE , 0 AS yjsl, 0 AS yysl, 0 AS jyrs, count( DISTINCT e.lsh ) AS jycs FROM sys_dzxxb AS b, sys_jcb AS c, sys_ltxxb AS e WHERE b.bm = c.lsh AND e.dzlsh = b.lsh GROUP BY c.mc ) AS temptable GROUP BY TYPE ";
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