无法限制一条数据多次出现的数据集

Question

SELECT FirstName, LastName, [description], ProjectName, StartOnDate, FinishOnDate
FROM Assignments AS A
JOIN Projects AS P ON A.ProjectID = P.ProjectID
JOIN Positions AS PO ON A.PositionCode = Po.PositionCode
JOIN Employees AS E ON E.EmployeeID = A.EmployeeID

这些是我需要的列，但我只需要出现两次的行。具体来说，我只需要有多个任务的员工。

下一个代码为我提供了重复的结果，但我似乎无法加入我正在寻找的结果集的其余表列。

SELECT A.EmployeeID
FROM Assignments AS A
GROUP BY A.EmployeeID 
HAVING COUNT(A.EmployeeID) > 1

Answer 1

该代码将 return 由 where 语句的子查询识别的每个员工的项目和职位。

SELECT FirstName, LastName, [description], ProjectName, StartOnDate, FinishOnDate
FROM Assignments AS A
JOIN Projects AS P ON A.ProjectID = P.ProjectID
JOIN Positions AS PO ON A.PositionCode = Po.PositionCode
JOIN Employees AS E ON E.EmployeeID = A.EmployeeID
WHERE EmployeeID in (SELECT A.EmployeeID
                     FROM Assignments AS A
                     GROUP BY A.EmployeeID 
                     HAVING COUNT(A.EmployeeID) > 1)

Answer 2

如果你没有庞大的数据集，你可以用困难的方式来做：

Select EmployeeID, FirstName, LastName, [description], ProjectName, StartOnDate,         
 FinishOnDate from (
   SELECT EmployeeID, FirstName, LastName, [description], ProjectName, StartOnDate,      FinishOnDate
   FROM Assignments AS A
   JOIN Projects AS P ON A.ProjectID = P.ProjectID
JOIN Positions AS PO ON A.PositionCode = Po.PositionCode
JOIN Employees AS E ON E.EmployeeID = A.EmployeeID) B
group by GROUP B.EmployeeID 
HAVING COUNT(B.EmployeeID) > 1

无法限制一条数据多次出现的数据集

Trouble limiting data set where a piece of data occurs more than once

sql

join

count

subquery

having