我試圖選擇最新的updated
(字段)pages
(表格),不包括隱藏的頁面(visible
=「n」)。但是,我想通過slug
對頁面進行分組,因此每個子彈只能得到一個結果。SQL LEFT JOIN問題
下面的查詢有點兒工作,但它只會選擇對每個塞最新更新的頁面 - 那麼,如果該頁面恰好被隱藏,它從結果:(刪除它在這種情況下,我只是想與塞最新更新頁面是可見。
SELECT `p1`.`id` AS `pID`, `p1`.`slug` AS `url`, `p1`.`revision`, `p1`.`title`, `p1`.`published`, `p1`.`updated`, (SELECT COUNT(*) FROM `pages` WHERE `slug` = `url` AND `visible` = "y") AS `revisionCount`, (SELECT COUNT(*) FROM `tests` WHERE `pageID` = `pID`) AS `testCount`
FROM `pages` `p1`
LEFT JOIN `pages` `p2` ON `p1`.`slug` = `p2`.`slug` AND `p1`.`updated` < `p2`.`updated`
WHERE `p2`.`updated` IS NULL AND `p1`.`visible` = "y"
ORDER BY `p1`.`updated` DESC
所以你想要每個slu latest的最新更新和可見頁?我猜更新是一個日期或int? – MrSoundless 2010-08-04 23:34:50
@MrSoundless:更新日期 – naburi 2010-08-05 00:09:28