将数据透视表结果压缩到 SQL 中的一行

Question

我想在 SQL 数据透视表中得到如下所示的单行结果

+------------+-----------+------------+----------+ |请求ID | IT 评论 | SO 评论 |批准 | +------------+-----------+------------+----------+ | 11111 | 09-19 | 09-20 | 09-21 | +------------+-----------+------------+----------+

但是，我无法摆脱列中的空值：

+------------+-----------+------------+----------+ |请求ID | IT 评论 | SO 评论 |批准 | +------------+-----------+------------+----------+ | 11111 | 09-19 |空 |空 | | 11111 |空 | 09-20 |空 | | 11111 |空 |空 | 09-21 | +------------+-----------+------------+----------+

以下是我的查询，谁能解释一下如何修改我的查询？谢谢！

   SELECT [Request_ID] [Request ID]
        ,[IT Review]
        ,[SO Review]
        ,[Approved]
    FROM (
        SELECT *
        FROM [RptChange].[dbo].[tRequestsAudit] a
        JOIN (
            SELECT [reqID] [Request_ID]
                ,MIN([reqUpdateDt]) [UpdateDT]
                ,MIN([AuditID]) AS EarliestAuditID
                ,[reqStatus] SubStatus
            FROM [RptChange].[dbo].[tRequestsAudit]
            WHERE [reqID] = 102943
            GROUP BY [reqStatus]
                ,[reqID]
            ) sub ON sub.[EarliestAuditID] = a.AuditID
        ) sub2
    PIVOT(MIN([UpdateDT]) FOR sub2.reqStatus IN (
                [IT Review]
                ,[SO Review]
                ,[Approved]
                )) AS P

Answer 1

尝试替换

SELECT *

与

SELECT DISTINCT sub.Request_ID, sub.UpdateDT,a.reqStatus

类似的东西：

   SELECT [Request_ID] [Request ID]
        ,[IT Review]
        ,[SO Review]
        ,[Approved]
    FROM (
        SELECT DISTINCT sub.Request_ID, sub.UpdateDT,a.reqStatus
        FROM [RptChange].[dbo].[tRequestsAudit] a
        JOIN (
            SELECT [reqID] [Request_ID]
                ,MIN([reqUpdateDt]) [UpdateDT]
                ,MIN([AuditID]) AS EarliestAuditID
                ,[reqStatus] SubStatus
            FROM [RptChange].[dbo].[tRequestsAudit]
            WHERE [reqID] = 102943
            GROUP BY [reqStatus]
                ,[reqID]
            ) sub ON sub.[EarliestAuditID] = a.AuditID
        ) sub2
    PIVOT(MIN([UpdateDT]) FOR sub2.reqStatus IN (
                [IT Review]
                ,[SO Review]
                ,[Approved]
                )) AS P

Answer 2

SELECT [Request_ID] [Request ID]
        ,[IT Review]
        ,[SO Review]
        ,[Approved]
    FROM (
        SELECT sub.[Request_ID], sub.SubStatus, sub.UpdateDT
        FROM [dbo].[tRequestsAudit] a
        JOIN (
            SELECT [reqID] [Request_ID]
                ,MIN([reqUpdateDt]) [UpdateDT]
                ,MIN([AuditID]) AS EarliestAuditID
                ,[reqStatus] SubStatus
            FROM [dbo].[tRequestsAudit]
            WHERE [reqID] = 1
            GROUP BY [reqStatus]
                ,[reqID]
            ) sub ON sub.[EarliestAuditID] = a.AuditID
        ) sub2
    PIVOT(MIN([UpdateDT]) FOR sub2.SubStatus IN (
                [IT Review]
                ,[SO Review]
                ,[Approved]
                )) AS P

Answer 3

可能是一种复杂的方法，但可以使用动态 SQL 压缩数据透视结果。 我设置的演示数据 (#data) 表示数据透视查询的输出，其中值最终交错排列，如问题中所述。

这里的逻辑是，将表链接到自身的内部查询（相关子查询），其中获取有序结果集的前 1 个值，会将与该 ID 相关的所有结果放在一行中。动态 SQL 使您能够生成查询，而无需跨许多行和列进行硬编码。

此解决方案是在 Transact SQL for MS SQL Server 中编写和测试的。

-- create temp table to store demo data
CREATE TABLE #data (Request_id int, 
                [IT Review] nvarchar(5),
                [SO Review] nvarchar(5),
                [Approved] nvarchar(5)
                )

-- add data to demo table
INSERT INTO #data
    VALUES (11111, '09-19', NULL, NULL),
        (11111, NULL, '09-20', NULL),
        (11111, NULL, NULL, '09-21')

-- view demo data
SELECT * FROM #data

-- view the column name data that will be used to generate the query
SELECT  name, column_id --INTO #table
FROM tempdb.sys.columns 
    WHERE object_id =
        object_id('tempdb..#data')
        ORDER BY column_id

-- declare variables to store the query in
DECLARE @inner_query AS VARCHAR(MAX)
DECLARE @outer_query AS VARCHAR(MAX)

-- generate the inner query, the part to take the only non null value (top 1) based on 
-- schema tables in the tempdb and relates this to the outer query via table alias t1. 
-- ensure to exclude the id column as this is only for the outer query
SET @inner_query = STUFF((SELECT '(SELECT TOP 1 ' + QUOTENAME(name) 
                                + ' FROM #data WHERE [Request_id] = t1.[Request_id] 
                                AND '
                                + QUOTENAME(name) 
                                + ' IS NOT NULL ) AS '
                                + QUOTENAME(name) + ','
                    FROM tempdb.sys.columns 
                    WHERE object_id = object_id('tempdb..#data')
                        AND name != 'Request_id'
                    GROUP BY name, column_id
                    ORDER BY column_id
                    FOR XML PATH(''), TYPE
                    ).value('.', 'NVARCHAR(MAX)') 
                ,1,1,'')

-- view inner query
SELECT @inner_query

-- clean inner query to add required bracket at start and remove the comma at the end
SET @inner_query = '(' + (SELECT SUBSTRING(@inner_query, 1, LEN(@inner_query)-1))

-- view cleaned inner query
SELECT @inner_query

-- set the outer query, to which the inner query matches (using WHERE id=id)
SET @outer_query = 'SELECT [Request_id], ' + @inner_query 
            + 'FROM #data t1 
            GROUP BY t1.[Request_id] ORDER BY t1.[Request_id]'

-- view final query
SELECT @outer_query

-- execute the query
EXECUTE(@outer_query)

DROP TABLE #data