TSQL Pivot 表行到列

Question

我在一个如下所示的表中有一些数据。我正在尝试运行一个查询，该查询将在每个 requestId 的单行上获取我的数据。我不需要日期或拒绝原因，只需要每个 groupId 的 eprojman 和 apvStatus

requestId - projMan1 - apvStatus1 - projMan2 - apvStatus2 - projMan3 - apvStatus3 等.. 对于所有 5 个 groupIds

requestId	groupId	entryDate	approvalDate	apvStatus	projMan	denialReason
1	1	2020-11-02	2019-07-25	APPROVED	rx1942	NULL
1	2	2020-11-02	2019-07-25	APPROVED	ma2674	NULL
1	3	2020-11-02	2019-07-25	APPROVED	cb9097	NULL
1	4	2020-11-02	2019-07-25	APPROVED	bj1763	NULL
1	5	2020-11-02	2019-07-25	APPROVED	tr5972	NULL
2	1	2020-11-02	NULL	NOT APPROVED	NULL	6
2	2	2020-11-02	NULL	PENDING	ma2674	NULL
2	3	2020-11-02	NULL	PENDING	cb9097	NULL
2	4	2020-11-02	NULL	PENDING	bj1763	NULL
2	5	2020-11-02	NULL	PENDING	tr5972	NULL

我一直在尝试使用 PIVOT 表，但我发现的所有示例都涉及汇总数据或其他内容。我只是非常想把 5 行变成每个 requestID 的 1 行

我唯一能想到的就是从同一个表中为每个 groupID 选择 5 次并将其合并，但这比见鬼要慢。必须是更好的方法

谢谢。

当前查询：

select group1.requestId
    , group1.apvStatus as apvStatus1
    , group1.projMan as projMan1
    , group2.apvStatus as apvStatus2
    , group2.projMan as projMan2
    , group3.apvStatus as apvStatus3
    , group3.projMan as projMan3
    ,group4.apvStatus as apvStatus4
    , group4.projMan as projMan4
    ,group5.apvStatus as apvStatus5
    , group5.projMan as projMan5
    ,group1.denialReason 
    INTO #TEMPBAOrganized
    from (
    select requestId, apvStatus, projMan, denialReason from #TEMPBULKAPPROVAL where groupId = 1) group1
    INNER JOIN 
    (select requestId, apvStatus, projMan, denialReason from #TEMPBULKAPPROVAL where groupId = 2) group2
    on group1.requestId = group2.requestId
    INNER JOIN
    (select requestId, apvStatus, projMan from #TEMPBULKAPPROVAL where groupId = 3) group3
    on group1.requestId = group3.requestId
    INNER JOIN
    (select requestId, apvStatus, projMan from #TEMPBULKAPPROVAL where groupId = 4) group4
    on group1.requestId = group4.requestId
    INNER JOIN
    (select requestId, apvStatus, projMan from #TEMPBULKAPPROVAL where groupId = 5) group5
    on group1.requestId = group5.requestId

Answer 1

你可以这样做：

SELECT
    requestId,
    approvalDate_1 = MAX(approvalDate_1),
    approvalDate_2 = MAX(approvalDate_2),
    approvalDate_3 = MAX(approvalDate_3),
    approvalDate_4 = MAX(approvalDate_4),
    approvalDate_5 = MAX(approvalDate_5), 
    projMan_1 = MAX(projMan_1),
    projMan_2 = MAX(projMan_2),
    projMan_3 = MAX(projMan_3),
    projMan_4 = MAX(projMan_4),
    projMan_5 = MAX(projMan_5)
FROM
(
SELECT
    requestId,
    groupId, 
    approvalDate,
    projMan,
    'approvalDate_' + CAST( groupId AS VARCHAR(2)) AS approvalDatePivot,
    'projMan_' + CAST( groupId AS VARCHAR(2)) AS projManPivot
FROM
  @tbl
) T
PIVOT (
  MAX(approvalDate) FOR approvalDatePivot IN ([approvalDate_1],[approvalDate_2],[approvalDate_3],[approvalDate_4],[approvalDate_5])
) pvt_1
PIVOT (
  MAX(projMan) FOR projManPivot IN ([projMan_1],[projMan_2],[projMan_3],[projMan_4],[projMan_5])
) pvt_2

GROUP BY requestId

Answer 2

对于多列的旋转，使用 CASE 表达式与聚合更容易。

select  t.requestId,
        projMan1    = max(case when t.groupId = 1 then t.projMan end),
        apvStatus1  = max(case when t.groupId = 1 then t.apvStatus end),
        projMan2    = max(case when t.groupId = 2 then t.projMan end),
        apvStatus2  = max(case when t.groupId = 2 then t.apvStatus end),
        projMan3    = max(case when t.groupId = 3 then t.projMan end),
        apvStatus3  = max(case when t.groupId = 3 then t.apvStatus end),
        projMan4    = max(case when t.groupId = 4 then t.projMan end),
        apvStatus4  = max(case when t.groupId = 4 then t.apvStatus end),
        projMan5    = max(case when t.groupId = 5 then t.projMan end),
        apvStatus5  = max(case when t.groupId = 5 then t.apvStatus end)
from    #TEMPBULKAPPROVAL t
group by t.requestId

注意：max 也是一个聚合函数