SQL嵌套查询总结

200 阅读 0 评论 132 点赞

我是靠谱客的博主轻松音响，最近开发中收集的这篇文章主要介绍SQL嵌套查询总结，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

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 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 ";