如何获得用逗号分隔的逗号值？

Question

我对SQL的工作，我有两个表

EId Ename 
1  john 
2  alex 
3  piers 
4  sara 

，第二个表是

PID PNAME EID 
1  mcndd 1 
2  carter 1 
3  leare 2 
4  jain 2 

结果应该是

EID count PID 
1  2  1 
1  2  2 
2  2  3 
2  2  4 

我要为this.i查询曾尝试过这样的

SELECT t1.EID, COUNT(t1.EID) count,PID 
from Employertable t1 
INNER JOIN persontable P ON P.EID=t1.EID 
Group By t1.EID Having Count(T1.EID) > 1 

Answer 1

你可以使用窗口功能来做到这一点。有了这些功能，您可以用非聚合数据合并汇总数据：

DECLARE @t1 TABLE (EID INT) 
DECLARE @t2 TABLE (PID INT, EID INT) 

INSERT INTO @t1 
VALUES (1), 
     (2), 
     (3), 
     (4) 
INSERT INTO @t2 
VALUES (1, 1), 
     (2, 1), 
     (3, 2), 
     (4, 2) 


SELECT * 
FROM (SELECT t1.EID , 
        COUNT(*) OVER (PARTITION BY t2.EID) AS C , 
        t2.PID 
      FROM  @t1 t1 
        JOIN @t2 t2 ON t2.EID = t1.EID 
     ) t 
WHERE t.C > 1   

输出：

EID C PID 
1 2 1 
1 2 2 
2 2 3 
2 2 4