sql - 在 UDF 中使用游标，返回具有不同表名称的列

Question

Create FUNCTION [dbo].[fn_GetStockDeatils]()
RETURNS @Results TABLE
(
PurchaseData nvarchar(50) NOT NULL 

)
AS
    BEGIN


    Declare @tableName varchar(25)
    Declare @PKKey numeric(18,0)

    DECLARE StockCursor CURSOR FOR Select tableName ,PKKey from INVM 
    OPEN StockCursor
    FETCH StockCursor INTO @tableName ,@PKKey 
       Begin

         Insert @Results Select PurchaseData from @tableName.PKKey =@PKKey 

       END      
    FETCH StockCursor INTO @tableName ,@PKKey 
    close StockCursor
    DEALLOCATE StockCursor


        Return  

    END

我已经写了这个，但它不能正常工作。@tableName包含表的名称。如果可能，请帮助我。

Answer 1

听起来您需要动态 SQL 命令，但您不能从函数中使用动态 SQL。为此，您必须创建存储过程。

CREATE PROCEDURE [dbo].[GetStockDeatils]
AS
BEGIN
DECLARE @tableName varchar(25),
        @PKKey numeric(18,0),
        @dsql nvarchar(max) = N''

IF OBJECT_ID('tempdb.dbo.#Results') IS NOT NULL DROP TABLE dbo.#Results
CREATE TABLE dbo.#Results(PurchaseData nvarchar(50) NOT NULL)

DECLARE StockCursor CURSOR LOCAL FAST_FORWARD FOR 
SELECT tableName ,PKKey 
FROM INVM 
OPEN StockCursor
FETCH NEXT FROM StockCursor INTO @tableName, @PKKey
WHILE @@FETCH_STATUS = 0
BEGIN 
  SET @dsql = 'Insert dbo.#Results Select PurchaseData from ' + @tableName + ' WHERE PKKey = ' + CAST(@PKKey AS varchar(10))
  EXEC sp_executesql @dsql  
  FETCH NEXT FROM StockCursor INTO @tableName, @PKKey 
END
CLOSE StockCursor
DEALLOCATE StockCursor

SELECT *
FROM dbo.#Results
END

EXEC [dbo].[GetStockDeatils]

SQLFiddle上的演示

创建视图的过程

CREATE PROCEDURE [dbo].[GetStockDeatils]
AS
BEGIN
DECLARE @dsql nvarchar(max) = N''
IF OBJECT_ID('dbo.v_Results') IS NOT NULL DROP VIEW dbo.v_Results
SELECT @dsql += 
  'UNION ALL SELECT PurchaseData FROM ' + tableName + 
  ' WHERE PKKey = ' + CAST(PKKey AS varchar(10))                
FROM dbo.INVM
SET @dsql = N'CREATE VIEW dbo.v_Results AS ' + STUFF(@dsql, 1, 10, '')
EXEC sp_executesql @dsql
END

EXEC [dbo].[GetStockDeatils]

SELECT *
FROM dbo.v_Results