組由分日期時間

Question

結果我試圖讓第一（最低）開始一個員工的日期：

SELECT a.StartDate, a.EmpID, b.fullname FROM Employees a 
LEFT JOIN dbo.info b ON a.EmpID = b.EmpID 
WHERE 
    type = 800 
    GROUP By EmpId 
    ORDER BY fullname 

結果與此類似：

StartDate | EmpId 
1992-12-01 00:00:00.000 | 7 
2014-01-01 00:00:00.000 | 7 
2015-01-01 00:00:00.000 | 7 
1992-12-01 00:00:00.000 | 10 
2014-01-01 00:00:00.000 | 10 
2015-01-01 00:00:00.000 | 10 
1992-01-01 00:00:00.000 | 16 
2014-01-01 00:00:00.000 | 16 
2015-01-01 00:00:00.000 | 16 

要得到的最低日每個員工我都試過這個，但是卻導致了一個錯誤。

SELECT MIN(a.StartDate), a.EmpID, b.fullname FROM Employees a 
LEFT JOIN dbo.info b ON a.EmpID = b.EmpID 
WHERE 
    type = 800 
    GROUP By EmpId 
    ORDER BY fullname 

什麼是正確的查詢得到如下結果：

StartDate | EmpId 
1992-12-01 00:00:00.000 | 7 
1992-12-01 00:00:00.000 | 10 
1992-01-01 00:00:00.000 | 16 

Answer 1

SELECT a.StartDate, a.EmpID, b.fullname 
FROM Employees a 
LEFT JOIN dbo.info b ON a.EmpID = b.EmpID 
WHERE type = 800 
AND NOT EXISTS (SELECT 'a' 
       FROM Employees a2 
       WHERE a.EmpID = a2.EmpID 
       AND a2.StartDate < a.StartDate 
       ) 

Answer 2

需要每個EmpID一個結果行，所以這是你應該列組由：

SELECT MIN(StartDate), EmpID 
FROM  Employees 
WHERE type = 800 AND EmpID BETWEEN 1 AND 500 
GROUP BY EmpID 

Answer 3

SELECT MIN(StartDate), EmpID FROM Absences 
WHERE type = 800 
AND EmpID BETWEEN 1 AND 500 
GROUP BY StartDate 

你的團隊是在錯誤的領域。

GROUP BY EmpID 

Answer 4

使用此查詢， 這將停止重複數據

SELECT Distinct StartDate, EmpID FROM Employees 

Answer 5

SELECT DISTINCT a.EmpID, b.fullname, a.StartDate FROM Employees a 
LEFT JOIN dbo.info b 
ON a.EmpID = b.EmpID 
WHERE type = 800  
ORDER BY a.StartDate, b.fullname ASC