Question

我有两张桌子，其中一张是“请求”，我有用户向我发送过朋友请求，或者我收到了朋友请求。在第二个表中，我记录了自己的入围用户。现在，我想要一起选择所有这些用户（我要求的人，请求我的人，我已入围的用户）。我正在使用联合查询，并根据列类型

区分它们

select Distinct userid,type,status from
(
select RequestSenderId as UserId,'requestedme' as type,'1' as status from tblrequest where RequestReceiverId=@UserId 

union
select RequestReceiverId as UserId,'requestedbyme' as type,'2' as status from tblrequest where RequestSenderId=@UserId 

union
select Shortlisteduserid as UserId,'Shortlisted' as type,'0' as status from tblshortlist where userid=@UserId
)

问题是我没有获得明确的用户ID，如果我也将其列入候选名单，他也向我发送了请求。

任何人都可以建议如何从结果中获取不同的用户ID。优先级是按要求获取用户标识而不是列入候选名单。

Answer 1

这可以帮到你。

select userid,type,status from
(
select Distint  RequestSenderId ,'requestedme' as type,'1' as status from tblrequest where ReceiverId=@UserId 

union ALL
select Distint  RequestReceiverId ,'requestedbyme' as type,'2' as status from tblrequest where SenderId=@UserId 

union ALL
select Distint  Shortlisteduserid ,'Shortlisted' as type,'0' as status from tblshortlist where userid=@UserId
)

Answer 2

以下怎么样？它可能不是最有效的解决方案..

WITH requestedMe (userid, type, status)
    AS (
        SELECT RequestSenderId AS UserId,'requestedme' AS type,'1' AS status 
        FROM tblrequest 
        WHERE ReceiverId=@UserId)
    requestedByMe (userid, type, status)
    AS (
        SELECT RequestReceiverId AS UserId,'requestedbyme' AS type,'2' AS status 
        FROM tblrequest 
        WHERE SenderId=@UserId
            AND NOT EXISTS (
                SELECT *
                FROM requestedMe
                WHERE requestedMe.userid = tblrequest.RequestReceiverId))
    shortListed (userid, type, status)
    AS (
        SELECT Shortlisteduserid AS UserId,'Shortlisted' AS type,'0' AS status 
        FROM tblshortlist 
        WHERE userid=@UserId
            AND NOT EXISTS (
                SELECT *
                FROM requestedMe
                WHERE requestedMe.userid = tblshortlist.Shortlisteduserid)
            AND NOT EXISTS (
                SELECT *
                FROM requestedByMe
                WHERE requestedByMe.userid = tblshortlist.Shortlisteduserid))
SELECT userid, type, status
FROM requestedMe
UNION
SELECT userid, type, status
FROM requestedByMe
UNION
SELECT userid, type, status
FROM shortListed

Answer 3

您可以使用排名功能（ROW_NUMBER或DENSE_RANK）来确定结果的优先级。

SELECT UserId, Type, Status
FROM (
    SELECT UserId, Type, Status
    , Priority = ROW_NUMBER() OVER (PARTITION BY UserID ORDER BY Type DESC)
    FROM (
        SELECT ReceiverId, RequestSenderId, 'requestedme', 1 FROM tblRequest
        UNION ALL
        SELECT SenderId, RequestReceiverId, 'requestedbyme', 2 FROM tblRequest
        UNION ALL
        SELECT UserId, Shortlisteduserid ,'Shortlisted', 0 FROM tblShortlist
    ) U (FilterUserId, UserId, Type, Status)
    WHERE FilterUserId = @UserId
) R
WHERE Priority = 1

当我有不同值的列时，如何获得不同的结果

3 个答案: