此查詢返回我需要給定具體traceid
值(50在本例中,這是存在兩個表中,tblResults
和tblTraces
一密鑰對數據:MySQL - 將這兩個查詢連同一個連接或子查詢一起加入?
SELECT count(changed)
FROM (
SELECT changed
FROM tblResults
WHERE traceid = 50
AND changed = 1
ORDER BY resultid DESC
LIMIT 0,20
) as R
我想運行鍼對此上述查詢幾乎每traceid
(因此,選擇每個traceid 20行,而不僅僅是traceid 50,所以3 traceid的將意味着60行)這個簡單的選擇下面獲取所需traceid
值:
SELECT `traceid` FROM `tblTraces` WHERE `enabled` = 1
如何將兩個查詢「粘合」在一起?
所以我想像類似下面的查詢,但由於子查詢返回多行,它不會工作(我想):
SELECT count(changed)
FROM (
SELECT changed
FROM tblResults
WHERE traceid = (
SELECT `traceid` FROM `tblTraces` WHERE `enabled` = 1
)
AND changed = 1
ORDER BY resultid DESC
LIMIT 0,20
) as R
向我們展示'SHOW的輸出CREATE TABLE tblResults;' – 2013-03-23 20:41:30
在表'tblTraces'是不同的'traceid'? – Justin 2013-03-23 20:41:50
@Justin是的,他們是 – jwbensley 2013-03-23 20:49:22