GROUP BY和列

Question

的選擇，我有以下查詢

SELECT McId, MAX(TimeDone) 
FROM Trace 
WHERE PcbId = 'C825514362' 
AND DeviceId <> 0 GROUP BY McId 

但我還需要從以下幾列Program，DeviceId獲取值，OrderNo

是否有可能以某種方式結合起來，在同一查詢？

該查詢應該在mssql，mysql和oracle下運行。

Answer 1

SELECT 
McId, 
MAX(TimeDone), 
Program, 
DeviceId, 
OrderNo 
FROM Trace 
WHERE PcbId = 'C825514362' AND DeviceId <> 0 
GROUP BY 
McId, 
Program, 
DeviceId, 
OrderNo 

Answer 2

您是否嘗試過以下構造？

SELECT McId, MAX(TimeDone),Program,DeviceId,OrderNo FROM Trace WHERE PcbId = 'C825514362' AND DeviceId <> 0 GROUP BY McId,Program,DeviceId,OrderNo 

Answer 3

爲什麼不能將Program，DeviceId，OrderNo添加到組中？

如果您回答它會生成更多行，因爲「Program，DeviceId，OrderNo」的值不同，您希望顯示哪個值？

你總是可以嵌入在你組一個子查詢通過獲得這個值，但再次，如果你有一個以上的可能性，您需要定義規則，拿出方案，例如

SELECT McId, MAX(TimeDone), 
     (select top 1 program from trace t2 where t2.McId = trace.McId) as program 
FROM Trace 
WHERE PcbId = 'C825514362' AND DeviceId <> 0 
GROUP BY McId 

Answer 4

三種解決方案

1. 考慮到你想要的Program,DeviceId,OrderNo

    
   SELECT McId, 
        MAX(TimeDone), 
        MAX(Program), 
        MAX(DeviceId), 
        MAX(OrderNo) 
   FROM Trace 
   WHERE PcbId = 'C825514362' AND DeviceId 0 
   GROUP BY McId; 
   

2. 的MAX考慮你想要剩餘的列逗號，~分開，分隔

    
   SELECT McId, 
        MAX(TimeDone), 
        GROUP_CONCAT('~', Program, '~', DeviceId, '~', OrderNo) 
   FROM Trace 
   WHERE PcbId = 'C825514362' AND DeviceId 0 
   GROUP BY McId 
   

3. 考慮要進行分組連同McId

    
   SELECT McId, 
        MAX(TimeDone), 
        Program, 
        DeviceId, 
        OrderNo 
   FROM Trace 
   WHERE PcbId = 'C825514362' AND DeviceId 0 
   GROUP BY McId, Program, DeviceId, OrderNo; 
   

Answer 5

嗯，我猜你想計劃，DEVICEID和OrderNo的值包含最大TimeDone的行。據我所知，你必須用子查詢來做到這一點。 類似的東西：

SELECT t.McID, t.Program, t.DeviceID, t.OrderNo, t.TimeDone 
FROM Trace t, 
    (SELECT MAX(TimeDone) as maxtime, McID 
FROM Trace 
GROUP BY McID) maxresults 
WHERE t.McID = maxresults.McID 
AND t.TimeDone= maxresults.maxtime;