Question

我有这张桌子

CREATE TABLE APmeasure 
(id_APmeasure INTEGER PRIMARY KEY AUTOINCREMENT 
 , RSSI TEXT, TimeOfMeasure DATETIME
 , BSSID TEXT, id_APm INTEGER NOT NULL 
 , FOREIGN KEY (id_APm) REFERENCES APTable (id_Ap) ON DELETE CASCADE)

我想提出一个查询，它会给我TimeOfMeasure和BSSID的明确结果，如下所示：

SELECT DISTINCT TimeOfMeasure, BSSID 
FROM APmeasure 
WHERE "condition"

但是这将检索表格中与DISTINCT查询相关的其他列。

我该怎么做？

Answer 1

执行不同/分组操作，
加入不同/分组操作的结果......

类似的东西：

SELECT [whichever columns you want]
  FROM APmeasure 
       JOIN (
           SELECT TimeOfMeasure, BSSID 
             FROM APmeasure 
            WHERE [condition]
         GROUP BY TimeOfMeasure, BSSID
       ) x
       ON x.TimeOfMeasure = APmeasure.TimeOfMeasure
   AND x.BSSID = APmeasure.BSSID
       [any other joins you need]

如何为其他列的SELECT DISTINCT查询添加另一列？

1 个答案: