如何在WHERE CLAUSE中使用DISTINCT以避免重復的行返回

Question

此SQL查詢的結果應返回一組6行。

SELECT baseFeeds.siteURL, feedFinishes.timeTaken, feedFinishes.timeSubmitted 
FROM feedFinishes 
LEFT OUTER JOIN baseFeeds 
ON feedFinishes.GUID = baseFeeds.GUID 
WHERE feedFinishes.nowDate = baseFeeds.nowDate 
AND baseFeeds.siteURL LIKE '%www.example.com%'

目前它返回18行，正確的6行重復3次。 我認為這個解決方案是讓另一個WHERE子句類似於：

WHERE DISTINCT feedFinishes.ID

經過研究，我嘗試過：

SELECT baseFeeds.siteURL, feedFinishes.timeTaken, feedFinishes.timeSubmitted 
FROM feedFinishes 
JOIN baseFeeds 
ON feedFinishes.GUID = baseFeeds.GUID 
WHERE baseFeeds.siteURL LIKE '%www.example.com%' AND feedFinishes.ID in
     (SELECT ID FROM feedFinishes GROUP BY ID HAVING COUNT(ID)=1);

在這里討論后發現

唉，這仍然會返回18行。 我相信答案與此類似

任何意見，將不勝感激。

Answer 1

您應該應用group by子句。

SELECT 
baseFeeds.siteURL, feedFinishes.timeTaken, feedFinishes.timeSubmitted
FROM feedFinishes 
JOIN baseFeeds 
ON feedFinishes.GUID = baseFeeds.GUID 
WHERE baseFeeds.siteURL LIKE '%www.example.com%' 
GROUP BY
baseFeeds.siteURL, feedFinishes.timeTaken, feedFinishes.timeSubmitted