[請益] 多資料表條件篩選的建立技巧
像下面這財經網站，裡面表列許多條件可供篩選
( http://www.wantgoo.com/hottipsearch.aspx )
我想問的是這些條件分散在其他資料表當中，是根據勾選的項目來做集合動作嗎?(ex1)
還是先把全部資料聯集載出，再根據不同條件去做where篩選呢?例如ex2
(((ex1)))
單純A條件
SELECT A.data1 FROM (SELECT data1 FROM A1) A where A條件
除了A條件之外，再勾選B條件
SELECT A.data1 FROM (SELECT data1 FROM A1) A
LEFT JOIN (SELECT FROM B1) B where A條件 and B條件
((( ex2 )))
但這樣效能是否會相對不好?
SELECT A.data1 FROM (SELECT data1 FROM A1) A
LEFT JOIN (SELECT FROM B1) B
LEFT JOIN (SELECT FROM C1) C ..........where A條件 and B條件.....
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