如何链接以下2个表来获得（如下所示）在SQL Server中的结果？'

Question

访问

LoginID, StaffName, qno, trackno, tmstamp 
1,  James,  1001, 1,  01-01-2011 
2,  John,  1002, 2,  01-01-2011 
2,  John,  1003, 3,  01-01-2011 

物质

content, trackno, tmstamp 
001,  1,  01-01-2011 
002,  1,  01-01-2011 
001,  2,  01-01-2011 
002,  2,  01-01-2011 
003,  2,  01-01-2011 
001,  3,  01-01-2011 

结果

StaffName, tmstamp, noOfQno, noOfContent 
James,  01-01-2011, 1,  2 
John,  01-01-2011, 2,  4 

Visit和Matter是2张桌子。

结果是我想要的结果。

我该如何做到这一点？

Answer 1

试试这个：

SELECT StaffName, tmstamp, noOfQno, noOfContent 
    FROM (
       SELECT StaffName, tmstamp, trackno, COUNT(1) noOfQno 
        FROM Visit 
       GROUP BY StaffName, tmstamp, trackno 
      ) a LEFT JOIN 
      (
       SELECT trackno, COUNT(1) noOfContent 
        FROM Matter 
       GROUP BY trackno 
      ) b 
    ON b.trackno = a.trackno 

Answer 2

同Cyber​​nates答案，但CTE：

;with MattersGrouped as (
    select trackno, COUNT(*) noOfContent 
    from Matter 
    group by trackno 
), 
VisitsGrouped as (
    select Staffname, trackno, tmstamp, COUNT(*) noOfQno 
    from Visit 
    group by Staffname, trackno, tmstamp 
) 
select t1.StaffName, t1.tmstamp, t2.noOfContent, t1.noOfQno 
from VisitsGrouped t1 left join MattersGrouped t2 on (t1.trackno = t2.trackno) 

Answer 3

SELECT 
    v.StaffName, 
    v.tmstamp, 
    noOfQno = COUNT(DISTINCT v.qno), 
    noOfContent = COUNT(m.content) 
FROM Visit v 
    LEFT JOIN Matter m ON v.trackno = m.tracno AND v.tmstamp = m.tmstamp 
GROUP BY v.StaffName, v.tmstamp