SQL Group by MAX（Date）

Question

我有以下查詢。每個駕駛執照號碼都有許多檢查日期。所以記錄如下：

InspectionDate   DriverLicenseNumber 
2010-01-02 00:00:00   123 
2010-01-05 00:00:00   123 
2011-01-05 00:00:00   345 


    SELECT 
MAX(InspectionDate), 
DriverLicenseNumber 
FROM #Test 
GROUP BY DriverLicenseNumber 

爲什麼我仍然得到多個日期和相同的駕駛執照號碼？

感謝

Answer 1

試試這個，它應該測試達的想法...

SELECT 
    MAX(InspectionDate), 
    CAST(DriverLicenseNumber AS INT) 
FROM 
    #Test 
GROUP BY 
    CAST(DriverLicenseNumber AS INT) 

或者，也許這...

SELECT 
    MAX(InspectionDate), 
    LTRIM(RTRIM(UPPER(DriverLicenseNumber))) 
FROM 
    #Test 
GROUP BY 
    LTRIM(RTRIM(UPPER(DriverLicenseNumber))) 

Answer 2

下面的代碼說明這並不是真正的問題，就像馬丁上面所說的，必須有別的事情上。

CREATE TABLE #test 
(
    a DATETIME, 
    id INT 
) 

INSERT INTO #test VALUES ('20100102', 123) 
INSERT INTO #test VALUES ('20100105', 123) 
INSERT INTO #test VALUES ('20110105', 345) 

SELECT MAX(a), id 
FROM #test 
GROUP BY id 

DROP TABLE #test 

Answer 3

只是改變DriverLicenseNumber在整數你表，然後您的查詢將按原樣運行。