How can I join on a stored procedure?

Question

I have a stored procedure that takes no parameters, and it returns two fields. The stored procedure sums up all transactions that are applied to a tenant, and it returns the

Answer 1

It has already been answered, the best way work-around is to convert the Stored Procedure into an SQL Function or a View.

The short answer, just as mentioned above, is that you cannot directly JOIN a Stored Procedure in SQL, not unless you create another stored procedure or function using the stored procedure's output into a temporary table and JOINing the temporary table, as explained above.

I will answer this by converting your Stored Procedure into an SQL function and show you how to use it inside a query of your choice.

CREATE FUNCTION fnMyFunc()
RETURNS TABLE AS
RETURN 
(
  SELECT tenant.ID AS TenantID, 
       SUM(ISNULL(trans.Amount,0)) AS TenantBalance 
  FROM tblTenant tenant
    LEFT JOIN tblTransaction trans ON tenant.ID = trans.TenantID
  GROUP BY tenant.ID
)

Now to use that function, in your SQL...

SELECT t.TenantName, 
       t.CarPlateNumber, 
       t.CarColor, 
       t.Sex, 
       t.SSNO, 
       t.Phone, 
       t.Memo,
       u.UnitNumber,
       p.PropertyName
FROM tblTenant t
    LEFT JOIN tblRentalUnit u ON t.UnitID = u.ID
    LEFT JOIN tblProperty p ON u.PropertyID = p.ID
    LEFT JOIN dbo.fnMyFunc() AS a
         ON a.TenantID = t.TenantID
ORDER BY p.PropertyName, t.CarPlateNumber

If you wish to pass parameters into your function from within the above SQL, then I recommend you use CROSS APPLY or CROSS OUTER APPLY.

Read up on that here.

Cheers