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SQL嵌套查詢總結

2020-10-29 21:54:59
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IT也有一段時間了,剛開始的時候``````
的困難主要是在編程語言上,數組,邏輯,算法,...
這些都過來了之后,困難就上升到數據庫設計上了.
以及數據邏輯.
一個優秀的系統,會集成優秀的程序和優秀的數據庫設計.
要做到這點得有足夠的經驗.
這是我寫的一個結合UINON的嵌套查詢.
將五個方面的報表放到一個臨時表里,再從臨時表里,將所要的數據查詢出來. 
復制代碼 代碼如下:

$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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