SQL嵌套查询总结 潇湘博客

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.





$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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