Question

I’m getting the error

A SELECT statement that assigns a value to a variable must not be combined with data-retrieval operations.

Here’s my SELECT statement.

SELECT A.vendor_id, **@vendor_employee** = A.vendor_employee_id
    , B.txt_first_name, B.txt_last_name,
    SELECT txt_Vendor_Employee_Detail_Element, 
        (CASE 
            WHEN txt_Vendor_Employee_Detail_Value <> '' 
                AND txt_Vendor_Employee_Detail_Value IS NOT NULL 
            THEN txt_Vendor_Employee_Detail_Value 
            ELSE CONVERT(VARCHAR, txt_Vendor_Employee_Detail_Date) 
        END) AS Vendor_Detail_Element_Value 
    FROM t_vendor_employee_detail 
    WHERE vendor_employee_id = **@vendor_employee**)

FROM...

Answer 1

Yes, basically you can’t return data and assign variables in the same select statement. What I think you intend to do is a correlated subquery which references an outer value.

That wolud look something like this:

SELECT A.vendor_id, A.vendor_employee_id
    , B.txt_first_name, B.txt_last_name,
    (SELECT d.txt_Vendor_Employee_Detail_Element
    FROM t_vendor_employee_detail d
    WHERE d.vendor_employee_id = A.Vendor_employee_id /* references outside the subqquery */)

FROM...

but you are also returning multiple rows in your subquery which should probably be rewritten as a join.

SELECT A.vendor_id, A.vendor_employee_id
    , B.txt_first_name, B.txt_last_name,
    d.txt_Vendor_Employee_Detail_Element, 
        (CASE 
            WHEN D.txt_Vendor_Employee_Detail_Value <> '' 
                AND d.txt_Vendor_Employee_Detail_Value IS NOT NULL 
            THEN d.txt_Vendor_Employee_Detail_Value 
            ELSE CONVERT(VARCHAR, d.txt_Vendor_Employee_Detail_Date) 
        END) AS Vendor_Detail_Element_Value 
FROM vendor_table_A A 
    INNER JOIN t_vendor_employee_detail d
         ON d.vendor_employee_id = A.vendor_employee_id
    INNER JOIN vendor_table_B B 
         ON...

These examples will give you the basic idea but we would really need the whole query to give you a complete solution.