[請益] 哪種寫法效率比較好?
【table1】
no | type
_________
01 | a
02 | a
01 | b
03 | a
02 | b
01 | c
(以下省略上萬筆)
【table2】
no | type
_________
02 | b
03 | a
01 | c
(以下省略上千筆)
join這兩張表時,下列哪種語法效能會比較好?
(1.)
SELECT a.no FROM table1 AS a INNER JOIN table2 AS b ON a.no = b.no WHERE a.type = a AND b.type = a
(2.)
SELECT a.no FROM table1 AS a INNER JOIN table2 AS b ON a.no = b.no AND a.type = b.type WHERE a.type = a
(3.)效能一樣
謝謝。
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◆ From: 114.36.211.42
※ 編輯: s861175 來自: 118.163.71.162 (06/30 10:12)
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06/30 11:18, , 1F
06/30 11:18, 1F
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06/30 11:19, , 2F
06/30 11:19, 2F
補充說明:因為要抓兩張表分別的欄位資訊,因為是範例所以省略了,不然應該是
SELECT a.no,a.info,b.info,(省略一堆欄位名) FROM
所以,希望是用join的方式
※ 編輯: s861175 來自: 118.163.71.162 (06/30 13:47)
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06/30 20:59, , 3F
06/30 20:59, 3F
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06/30 21:00, 4F
推
07/01 09:38, , 5F
07/01 09:38, 5F
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07/01 09:41, , 6F
07/01 09:41, 6F
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07/02 17:23, , 7F
07/02 17:23, 7F
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07/04 19:36, , 8F
07/04 19:36, 8F