從類似行中選擇每個分鐘（日期）？

Question

這是表Posts結構（也有說是沒有問題的重要其他列）：

Verb | Object | Date 

我被動詞分組，然後對象，將所有類似的行，這是我當前的查詢：

SELECT * FROM Posts GROUP BY Verb, Object 

我需要知道每個組中最老的行的日期。如何才能做到這一點？

Answer 1

約

SELECT Verb, 
     Object, 
     MIN(date) OldestDate 
FROM Posts 
GROUP BY Verb, Object 

如何看一看GROUP BY (Aggregate) Functions

Answer 2

每個組中得到最古老的日期，那麼試試這個：

SELECT Verb, Object, MIN(`date`) AS min_date 
FROM Posts 
GROUP BY Verb, Object; 

如果你想獲取其最古老的日期的記錄在每個組中，然後試試這個：

然後重新啓動MyS QL服務器。

SELECT a.* 
FROM Posts a 
    INNER JOIN (SELECT Verb, Object, MIN(`Date`) AS `Date` 
       FROM Posts 
       GROUP BY Verb, Object 
       ) b 
       ON a.Verb = b.Verb 
        AND a.Object = b.Object 
        AND a.`Date` = b.`Date`;