SQL Multiple Joins Query

Question

这里我有两个表委员会大学和学院。 表的结构是这样的

committee_colleges

    committeeCollegeId collegeId committeeMemberId
    1                  2         1
    2                  2         2 
    3                  3         2

我从委员会成员表中存储委员会会员。一个学院可以有多个委员会成员。如何查询只显示分配给特定委员会成员的大学。 例如，如果id = 2的committeeMember已经登录，我想通过id = 2,3显示大学。

在大学的桌子上我喜欢这个，

    collegeId typeName
    1         AICTE
    2         NCTE
    3         NTCS

这是委员会成员表

    committeeMemberId name
    1                 xyz
    2                 abc 

现在我正在写这样的东西，但我知道它错了，因为我不知道如何从大学学习桌上拿走它，因为我正在展示学院的细节。

SELECT cc.committeeCollegeId as committeeCollegeId,
       c.collegeId as collegeId,
       cc.committeeMemberId as committeeMemberId
FROM committee_college as cc
left outer join College as c
    on cc.collegeId = c.collegeId
where cc.committeeMemberId=:committeeMemberId
order by cc.committeeCollegeId asc

任何人都可以根据其对特定委员会成员的任命来说明如何展示大学吗？

Answer 1

你很接近，你需要INNER JOIN而不是LEFT JOIN：

SELECT  DISTINCT C.typeName --<<== put here all the columns that you want in output
FROM    committee_colleges CC
        INNER JOIN college C
            ON C.collegeId = CC.collegeId
WHERE   CC.committeeMemberId = 2 --<<== your input parameter

编辑：添加了DISTINCT

希望它有所帮助。

Answer 2

您可以在下面的sql语句中使用相同的

DECLARE @committeeMemberId INT = 2  -- Id of Committee member

;WITH CTE_MemberCommittee AS
(
    SELECT  CollegeId 
    FROM    committee_colleges
    WHERE   committeeMemberId = @committeeMemberId
)

SELECT  collegeId, typeName
FROM    college
WHERE   collegeId IN (SELECT CollegeId FROM CTE_MemberCommittee)

Answer 3

试试这个：

DECLARE @LoginCommitteeMemberId INT=2
SELECT t2.Name AS MemberName,
       t3.TypeName AS CollageName
  FROM committee_college t1
   INNER JOIN Committee_Member t2 
    ON t1.committeeMemberId = t2.committeeMemberId 
  INNER JOIN College as t3 
    ON t1.collegeId = t3.collegeId 

  WHERE t1.committeeMemberId = @LoginCommitteeMemberId

Answer 4

您可以使用简单的内部联接，

如果你想基于memberId的collegename使用以下查询，

select a.collegeid,a.typeName from
college a, committee_colleges b, committe_member c
where a.collegeid = b.collegeid and
b.committeememberid = c.committeeMemberId
and c.committeeMemberId = '2'

如果你想根据committemember名称使用collegename，那么使用以下查询，

select a.collegeid,a.typeName from
college a, committee_colleges b, committe_member c
where a.collegeid = b.collegeid and
b.committeememberid = c.committeeMemberId
and c.Name = 'xyz'

希望它会有所帮助。