Query saved in table to run in different query's where clause - sql

Question

I have a table that have a list of "Reports" or "Correspondence Letters" (html files). This list will appear in a dropdown in a website. Some of these items will need a "check" to see if they are allowed to be added to the dropdown.
An example of how this table (I removed columns that was not necessary to display):
In this table there is a column "Cor_PolNeedCheck_ToShow". This value links to a different table where the query for that file is stored.
From here I need to create a query that will build the actual list that will be displayed. But in order to do that I need to run the query that is in the second table to perform the check. I've created the following query to do this and it brings back the expected results:
DECLARE #retvalue INT
DECLARE #Paramater NVARCHAR(20) = '241215'
DECLARE #Cor_GroupCde NVARCHAR(10) = 248
DECLARE #Statement NVARCHAR(500);
SELECT #Statement = (SELECT Lookup_Query + #Paramater FROM [dbo].[Ref_Lookup]
WHERE Lookup_ID = (Select Cor_PolNeedCheck_ToShow FROM dbo.Ref_Correspondence WHERE Cor_Group_Cde = #Cor_GroupCde));
EXEC #retvalue = sp_executesql #Statement;
PRINT #retvalue
This value needs to be passed into a query again to verify each record to show or not to show. This is the query that will run to show the items (I have added the #retvalue of the above in the query just to show what it needs to do). This query is in a stored proc where the #Paramater will be passed (above) from the application and then to be used as needed for the below (as above query needs to fit into this one).
SELECT Cor_Group_Cde, Cor_Desc
FROM Ref_Correspondence
WHERE Cor_Show = 'Y' AND Cor_Prod_List Like '%#' + #ProdID + '#%'
AND (Cor_PolNeedCheck_ToShow IS NULL OR --#retValue > 0)
The problem I'm facing is that I need to get the #retValue into the where clause.
I have though of a stored proc, but a stored proc cannot be called in a where clause. I then though of a user defined function, but the problem there is that you cannot call a stored proc ("sp_executesql") in a function.
Due to company standards I cannot do this within the application either. Is there a way around this or is there a way to do this that I maybe missed with the above?
-------------------- EDIT ---------------------
The function I created looks like this:
USE [DBName]
GO
/****** Object: UserDefinedFunction [dbo].[ufn_CorrespondenceCheckResult] Script Date: 4/11/2019 5:35:04 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER FUNCTION [dbo].[ufn_CorrespondenceCheckResult]
(
#Paramater nvarchar(20),
#Cor_GroupCde nvarchar(10)
)
RETURNS int
AS
BEGIN
DECLARE #Statement nvarchar(MAX);
DECLARE #Return int;
set #Return = 0;
SELECT #Statement = (SELECT Lookup_Query + #Paramater FROM [dbo].[Ref_Lookup]
WHERE Lookup_ID = (Select Cor_PolNeedCheck_ToShow FROM dbo.Ref_Correspondence WHERE Cor_Group_Cde = #Cor_GroupCde));
EXEC #Return = sp_executesql #Statement;
return #Return;
END
Running the above function in my script gives me an error of "Only functions and some extended stored procedures can be executed from within a function.":
SELECT Cor_Group_Cde, Cor_Desc
FROM Ref_Correspondence
WHERE Cor_Show = 'Y' AND Cor_Prod_List Like '%#' + #ProdID + '#%'
AND (Cor_PolNeedCheck_ToShow IS NULL OR ((SELECT [dbo].[ufn_CorrespondenceCheckResult] (#Paramater,#Cor_GroupCde)) > 0))

Answer 1

It would be better to convert your Stored Procedure into a Function, if possible. Then you can use function in WHERE clause.
If you can't convert it into the function then better to execute the SP and store the full result in a Variable. Now you can use This table in WHERE clause.

Answer 2

You should store the result of the Stored Procedure in a variable in then use that in your next statement's condition. You can use an OUTPUT parameter to return the value of from the Stored Procedure.
DECLARE #count INT
EXEC FindProductByModel --CREATE a stored procedure FindProductByModel instead of a function
#Paramater = '241215',
#Cor_GroupCde = '248',
#retvalue= #count OUTPUT --#retval is an output paramater of your stored procedure
SELECT Cor_Group_Cde, Cor_Desc
FROM Ref_Correspondence
WHERE Cor_Show = 'Y' AND Cor_Prod_List Like '%#' + #ProdID + '#%'
AND (Cor_PolNeedCheck_ToShow IS NULL OR #count>0)