Question

我在SQL Server中有两个相关的表，一对多关系（申请人，参考）。

我想要一个视图，它将从Applicant表中检索所有数据，并在视图中添加另一列，告诉我“完成”列为True的相关参考行数量。

Answer 1

使用子查询这样的东西：

select applicantfield1, applicantfield2, 
  (select count(*) from 
  reference where reference.applicantkey = applicant.applicantkey 
  and reference.complete = 1) AS referencecount
from applicant

除非完整字段在申请人表格中（不在参考表格中）。如果是这样，那就更像是这样：

select applicantfield1, applicantfield2, 
  (select count(*) from 
  reference where 
  reference.applicantkey = applicant.applicantkey) AS referencecount
from applicant
where applicant.complete = 1

Answer 2

如下所示。你需要加入一张桌子。这将处理申请人也没有真正参考的地方。

SELECT A.*, isnull(r.comptotal,0) as CompleteTotal 
FROM Applicant as a Left Join 
   (SELECT ApplicantId, Count(Complete) as comptotal
    FROM Reference Where Complete=1 Group by ApplicantID) as r 
    on a.ApplicantId = r.applicantId

SQL Server View从相关表中获取计数，其中column =“True”

2 个答案: