Question

empid   projectId   TaskID
100     500           1
100     501           1
100     502           1
101     500           2
101     500          5
101     500          1
102     400          1
103     300          2
104     300          2
105     300          2

我试图根据项目ID列出仅在多个项目上工作的员工。我试过了distinct和GROUP BY。但我无法准确地理解它。

从上表中的

我期待像这样的结果

 empid   projectId  
    100     500         
    100     501          
    100     502

Answer 1

试试这个（修订后的代码）

SELECT DISTINCT EmpId, ProjectId
FROM TableX
WHERE EmpId IN 
(
    SELECT EmpId
    FROM TableX
    GROUP BY EmpId
    HAVING COUNT (DISTINCT ProjectId) > 1
)

这应该给你

EmpId       ProjectId
----------- -----------
100         500
100         501
100         502

3 row(s)

修改在评论

中为OP附加问题添加的内容

给你一个计数的计数ProjectIds意味着GROUP BY将处于EmpId级别并且不需要子查询

SELECT EmpId, Count (Distinct ProjectId) Projects
FROM TableX
GROUP BY EmpId

要为具有多个项目的所有员工计算项目数，请执行以下操作

SELECT EmpId, Count (Distinct ProjectId) Projects
FROM TableX
GROUP BY EmpId
Having Count (Distinct ProjectId) > 1

Answer 2

您还可以使用窗口COUNT()：

WITH counted AS (
  SELECT
    empid,
    projectId,
    COUNT(DISTINCT projectId) OVER (PARTITION BY empid) AS ProjectCount
  FROM atable
)
SELECT DISTINCT
  empid,
  projectId
FROM counted
WHERE ProjectCount > 1

参考文献：

Answer 3

SELECT y.empid, y.projectId
    FROM (SELECT empid
              FROM YourTable
              GROUP BY empid
              HAVING COUNT(*) > 1) t
        INNER JOIN YourTable y
            ON t.empid = y.empid
    ORDER BY y.empid, y.projectId

不同记录的计数 - SQL

3 个答案: