Question

是否可以在MSSQL中使用表值函数来获取属性并使用Pivot函数生成关联的SQL语句？

CREATE FUNCTION dbo.fnPivot (@EntityTypeID int)
RETURNS TABLE
AS
BEGIN
    DECLARE @SQL varchar(MAX);
    DECLARE @COLS varchar(MAX);

    select @COLS=coalesce(@COLS+',','')+'['+Name+']'from c_EntityAttribute WHERE EntityTypeID = @EntityTypeID;

    SET @SQL = 'SELECT * FROM (SELECT EntityInstanceID, AttributeName, Value FROM v_EntityElementData WHERE EntityTypeID = 1) as s';
    SET @SQL = @SQL + 'PIVOT ( MIN(Value) FOR AttributeName IN (' + @COLS + ') ) AS p';

    RETURN EXEC sp_ExecuteSQL @SQL ;
END

Answer 1

不幸的是，除了存储过程外，SQL Server会跟踪所有视图，函数等输出的表定义。因此，列和类型不能在输入上动态更改。

出于这个原因，我从未发现PIVOT算子有用。通常，获取不同列数据的唯一方法是将其视为XML。

你出于什么原因转动它？这通常是一个UI问题，因此我建议在UI或SSRS等处进行。

Answer 2

表值函数必须始终返回指定的模式，因此这是不可能的。

Answer 3

这是我为适应这种功能所做的一些事情（作为一种观点，但功能将采用相同的方法）。我们将其粘贴在每个安装脚本的末尾，因此当对要旋转的表进行任何更改时，它们将在重新生成的视图中被拾取。

IF EXISTS (SELECT *
       FROM   sys.objects
       WHERE  object_id = Object_id(N'[dbo].[vwYourView]')
              AND type IN ( N'V' ))
BEGIN
  DROP VIEW [dbo].[vwYourView]
END
GO                            

Declare @cols VARCHAR(MAX)

Select @cols = COALESCE(@cols + ',[' + YourColumn+ ']',
                                 '[' + YourColumn+ ']')
                                 FROM YourTable
                                 Order By YourColumn

DECLARE @query VARCHAR(MAX)
Set @query =
N'
Create View vwYourView
AS
Select * FROM YourTable
Pivot (
    MAX(YourVal)
    FOR YourColumn IN( '+
        @cols
    +')
) AS pvt
'

Execute(@query)

Select * FROM [vwYourView]

Answer 4

我已经制作了以下程序来动态调整表格中的所有值。

CREATE OR ALTER PROC dbo.spDynamicPivot (
  @Query NVARCHAR(MAX)              --The query to pivot
, @AggregateFunction NVARCHAR(MAX)  --The aggregation function surrounding the column name to be pivoted
, @ValueColumn NVARCHAR(MAX)        --The value column from which to create columns
, @ResultTable NVARCHAR(MAX) = NULL --An optional table name into which the results will be stored. Note, this unfortunately will not work with #temp tables.
) AS BEGIN

  SET XACT_ABORT ON;
  SET NOCOUNT ON;

  DECLARE @cols NVARCHAR(MAX);

  DECLARE @sql NVARCHAR(MAX) = 'SELECT @cols = ISNULL(@cols + '','', '''') + ''['' + Val + '']'' FROM (SELECT DISTINCT Val = ' + @ValueColumn + ' FROM (' + @Query + ') a) b;';
  DECLARE @paramDef NVARCHAR(MAX) = '@cols NVARCHAR(MAX) OUTPUT';

  EXEC sp_executesql @sql, @paramDef, @cols = @cols OUTPUT;

  DECLARE @resultSetSql NVARCHAR(MAX) = IIF(ISNULL(@ResultTable, '') <> '', 'INTO ' + @ResultTable + ' ', '');
  SET @sql = 'SELECT * ' + @resultSetSql + 'FROM (' + @Query + ') q PIVOT( ' + @AggregateFunction + ' FOR ' + @ValueColumn + ' IN (' + @cols + ') ) p';

  EXEC sp_executesql @sql;

END

用法：

DROP TABLE IF EXISTS #t;
CREATE TABLE #t (Name VARCHAR(50), Age INT, NetWorth FLOAT);
INSERT INTO #t VALUES 
('Bill', 50, 250),
('Barb', 17, 15),
('Fred', 25, 30),
('Bill', 25, 100),
('Kahless', 90000, 4E10) 

--Displaying results directly
EXEC dbo.spDynamicPivot @Query = 'SELECT * FROM #t', @AggregateFunction = 'AVG(NetWorth)', @ValueColumn = 'Name'

--Or writing them into a table for additional use
DROP TABLE IF EXISTS tempdb.dbo.MyTable;
EXEC dbo.spDynamicPivot @Query = 'SELECT * FROM #t', @AggregateFunction = 'AVG(NetWorth)', @ValueColumn = 'Name', @ResultTable = 'tempdb.dbo.MyTable'

SELECT * FROM tempdb.dbo.MyTable

返回动态数据的SQL函数

4 个答案: