sql – 从已连接表的列表中选择唯一列名

我有一个表列表,可以通过相同的PK列连接在一起.由于这个表列表可能因项目而异,我想创建一个足够动态的查询来从这些表中提取所有唯一列.

For example,I have three tables below:
Table A (PK field,column1,column 2)
Table B (PK field,column3,column 4)
Table C (PK field,column5,column 5)

这三个表连接在“PK字段”列上,我希望查询输出类似于：

PK field  column1  column2  column3  column4  column5
..data..  ..data.. ..data.. ..data.. ..data.. ..data..

最后,此查询将成为SQL函数或SP的一部分,因此用户可以定义表的列表,并在开头的PK字段,然后执行它将返回我的预期输出与数据集.

我想在下面使用这个查询,但结果不是我喜欢的：

SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = ''

有关如何设计此SP或功能的任何建议,将不胜感激.

提前致谢.

两个示例表的DDL：

CREATE TABLE [dbo].[G_bDEM](
    [blaiseKey_code] [nvarchar](255) NULL,[qSex] [int] NULL,[qDOB] [datetime] NULL,[qDOBNR] [int] NULL,[qAge] [int] NULL,[qAgeNR] [int] NULL,[qAgeRange] [int] NULL,[qAge15OrOver] [int] NULL,[qNotEligible] [nvarchar](1) NULL,[qBornInNZ] [int] NULL,[qCountryOfBirth] [nvarchar](2) NULL,[qArriveNZYr] [int] NULL,[qArriveNZYrNR] [int] NULL,[qArriveNZMth] [int] NULL,[bDEM_BOP_qHowManyRaised] [int] NULL,[bDEM_BOP_q1stParentBornNZ] [int] NULL,[bDEM_BOP_q2ndParentBornNZ] [int] NULL,[bDEM_BOP_qHowManyParentBornNZ] [int] NULL,[qMaoriDescent] [int] NULL,[qSchQual] [int] NULL,[qSchQualOth] [nvarchar](200) NULL,[qSchQualOthNR] [int] NULL,[qSchQualYr] [int] NULL,[qSchQualYrNR] [int] NULL,[qPostSchQual] [int] NULL,[q3MthsStudy] [int] NULL,[qHighestQual] [int] NULL,[qHighestQualOth] [nvarchar](200) NULL,[qHighestQualOthNR] [int] NULL,[qHighestQualYr] [int] NULL,[qHighestQualYrNR] [int] NULL,[qWorkIntro] [nvarchar](1) NULL,[qDidPaidWork] [int] NULL,[qAwayFromWork] [int] NULL,[qFamilyBusWork] [int] NULL,[bDEM_WOR_qPaidWorkIntro] [nvarchar](1) NULL,[bDEM_WOR_qJobsNum] [int] NULL,[bDEM_WOR_qJobsNumNR] [int] NULL,[bDEM_WOR_tabDEM_T2_fTotMins] [int] NULL,[bDEM_WOR_q2JobsNoHrsIntro] [nvarchar](1) NULL,[bDEM_WOR_q2Jobs2HrsIntro] [nvarchar](1) NULL,[bDEM_WOR_q2Jobs1HrsIntro] [nvarchar](1) NULL,[bDEM_WOR_qOccupation] [nvarchar](200) NULL,[bDEM_WOR_qOccupationNR] [int] NULL,[bDEM_WOR_qMainTasks] [nvarchar](200) NULL,[bDEM_WOR_qMainTasksNR] [int] NULL,[bDEM_WOR_qFeelAboutJob] [int] NULL,[bDEM_WOR_qEmployArrangement] [int] NULL,[bDEM_WOR_qPermEmployee] [int] NULL,[qHasJobToStart] [int] NULL,[qLookedForWork] [int] NULL,[qJobSearchA] [int] NULL,[qJobSearchB] [int] NULL,[qJobSearchC] [int] NULL,[qJobSearchD] [int] NULL,[qJobSearchE] [int] NULL,[qJobSearchF] [int] NULL,[qJobSearchG] [int] NULL,[qJobSearchH] [int] NULL,[qJobSearchI] [int] NULL,[qJobSearchOth] [nvarchar](200) NULL,[qJobSearchOthNR] [int] NULL,[qCouldStartLastWk] [int] NULL,[qIncTotalAmt] [int] NULL,[fCountryName] [nvarchar](60) NULL
     ) ON [PRIMARY]

    GO

CREATE TABLE [dbo].[G_bLWW](
    [blaiseKey_code] [nvarchar](255) NULL,[qThingsWorthwhileScale] [int] NULL
 ) ON [PRIMARY]

解决方法

查询：

SET NOCOUNT ON

IF OBJECT_ID (N'dbo.A') IS NOT NULL
   DROP TABLE dbo.A

IF OBJECT_ID (N'dbo.B') IS NOT NULL
   DROP TABLE dbo.B

IF OBJECT_ID (N'dbo.C') IS NOT NULL
   DROP TABLE dbo.C

CREATE TABLE dbo.A (PK_field INT PRIMARY KEY,column1 INT,column2 INT)
CREATE TABLE dbo.B (PK_field INT PRIMARY KEY,column3 INT,column4 INT)
CREATE TABLE dbo.C (PK_field INT PRIMARY KEY,column5 INT,[column 6] INT)

INSERT INTO dbo.A (PK_field,column2)
VALUES (1,1,2),(2,2) 

INSERT INTO dbo.B (PK_field,column4)
VALUES (2,3,4) 

INSERT INTO dbo.C (PK_field,[column 6])
VALUES (1,5,6),(3,6) 

DECLARE @SQL NVARCHAR(MAX)

;WITH cte AS 
(
    SELECT 
          column_name = '[' + c.name + ']',table_name = '[' + s.name + '].[' + o.name + ']'
    FROM sys.columns c WITH (NOLOCK)
    JOIN sys.objects o WITH (NOLOCK) ON c.[object_id] = o.[object_id]
    JOIN sys.schemas s WITH (NOLOCK) ON o.[schema_id] = s.[schema_id]
    WHERE o.name IN ('A','B','C')
        AND s.name = 'dbo'
        AND o.[type] = 'U'  
),unicol AS (
    SELECT TOP 1 column_name 
    FROM cte 
    GROUP BY cte.column_name
    HAVING COUNT(cte.column_name) > 1
),cols AS 
(
    SELECT DISTINCT column_name 
    FROM cte    
),tbl AS 
(
    SELECT DISTINCT table_name
    FROM cte
),rs AS 
(
    SELECT 
          tbl.table_name,column_name = ISNULL(cte.column_name,cols.column_name + ' = NULL')
    FROM cols
    CROSS JOIN tbl
    LEFT JOIN cte ON cols.column_name = cte.column_name AND cte.table_name = tbl.table_name
),rs2 AS (
    SELECT uni = ' UNION ALL' + CHAR(13) + 'SELECT ' + STUFF((
        SELECT ',' + rs.column_name
        FROM rs
        WHERE tbl.table_name = rs.table_name
        GROUP BY rs.column_name
        ORDER BY rs.column_name
        FOR XML PATH(''),TYPE).value('.','NVARCHAR(MAX)'),2,'') + 
        ' FROM ' + table_name
    FROM tbl
) 
SELECT @SQL = 'SELECT 
' + STUFF((
    SELECT CHAR(13) + ',' + ISNULL(unicol.column_name,cols.column_name + ' = MAX(' + cols.column_name + ')')
    FROM cols
    LEFT JOIN unicol ON cols.column_name = unicol.column_name
    FOR XML PATH(''),' ')
 + ' 
FROM 
(' + STUFF((
    SELECT CHAR(10) + uni
    FROM rs2
    FOR XML PATH(''),11,'') + CHAR(13) + 
    ') t 
GROUP BY ' + (SELECT column_name FROM unicol)

PRINT @SQL

EXECUTE sys.sp_executesql @SQL

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