Is it possible to create a temporary table in a View and drop it after select?

I need to alter one view and I want to introduce 2 temporary table before the SELECT.

Is this possible? And how can I do it?

ALTER VIEW myView
AS 

SELECT *
INTO #temporary1

SELECT *
INTO #temporary2

SELECT * FROM #temporary1
UNION ALL 
SELECT * FROM #temporary1

DROP TABLE #temporary1
DROP TABLE #temporary2

When I attempt this it complains that ALTER VIEW must be the only statement in the batch.

How can I achieve this?

Solution 1:

No, a view consists of a single SELECT statement. You cannot create or drop tables in a view.

Maybe a common table expression (CTE) can solve your problem. CTEs are temporary result sets that are defined within the execution scope of a single statement and they can be used in views.

Example (taken from here) - you can think of the SalesBySalesPerson CTE as a temporary table:

CREATE VIEW vSalesStaffQuickStats
AS
  WITH SalesBySalesPerson (SalesPersonID, NumberOfOrders, MostRecentOrderDate)
      AS
      (
            SELECT SalesPersonID, COUNT(*), MAX(OrderDate)
            FROM Sales.SalesOrderHeader
            GROUP BY SalesPersonID
      )
  SELECT E.EmployeeID,
         EmployeeOrders = OS.NumberOfOrders,
         EmployeeLastOrderDate = OS.MostRecentOrderDate,
         E.ManagerID,
         ManagerOrders = OM.NumberOfOrders,
         ManagerLastOrderDate = OM.MostRecentOrderDate
  FROM HumanResources.Employee AS E
  INNER JOIN SalesBySalesPerson AS OS ON E.EmployeeID = OS.SalesPersonID
  LEFT JOIN SalesBySalesPerson AS OM ON E.ManagerID = OM.SalesPersonID
GO

Performance considerations

Which are more performant, CTE or temporary tables?

Solution 2:

You can achieve what you are trying to do, using a Stored Procedure which returns a query result. Views are not suitable / developed for operations like this one.

Solution 3:

Not possible but if you try CTE, this would be the code:

ALTER VIEW [dbo].[VW_PuntosDeControlDeExpediente]
AS
    WITH TEMP (RefLocal, IdPuntoControl, Descripcion) 
    AS 
    (
        SELECT 
              EX.RefLocal
            , PV.IdPuntoControl
            , PV.Descripcion
        FROM [dbo].[PuntosDeControl] AS PV
        INNER JOIN [dbo].[Vertidos] AS VR ON VR.IdVertido = PV.IdVertido
        INNER JOIN [dbo].[ExpedientesMF] AS MF ON MF.IdExpedienteMF = VR.IdExpedienteMF
        INNER JOIN [dbo].[Expedientes] AS EX ON EX.IdExpediente = MF.IdExpediente
    )
    SELECT 
          Q1.[RefLocal]
        ,    [IdPuntoControl] = ( SELECT MAX(IdPuntoControl) FROM TEMP WHERE [RefLocal] = Q1.[RefLocal] AND [Descripcion] = Q1.[Descripcion] )
        , Q1.[Descripcion]
    FROM TEMP AS Q1
    GROUP BY Q1.[RefLocal], Q1.[Descripcion]
GO