Question

I have two select queries to use in my project for getting data and displaying it in my web page. I want to join them so that I need to access data only once. But I don’t know how to join them as one of the query contains group function. Could you help me? Thanks in Advance.

Answer 1

One way to solve this would be to do the job in several steps. Before joining the result set to the query, you’ll need to save it in a temporary table or table variable. (A temporary table may be preferable if you are expecting a large result set.)

Basically, your query would change to something like this:

/* prepare the storage */
IF OBJECT_ID('tempdb..#sp_results') IS NOT NULL
  DROP TABLE #sp_results;
CREATE TABLE #sp_results (
  /* the types may be wrong, please modify as necessary */
  currency_cd int,
  salary decimal(10,2)
);

/* save the results of the SP */
INSERT INTO #sp_results
EXEC SP_name arguments…

/* use the saved results in your query */
SELECT
  your present columns,
  tmp.currency_cd,
  tmp.salary
FROM
  your present joins
  LEFT OUTER JOIN #sp_results AS tmp ON a proper join condition
;

The problem is, though, your SP is designed to return results for an individual employee while the query seems to be retrieving data for multiple employees. To resolve the issue, you could add an employee_code column to the temporary table and get/save the results for every employee one by one, in a cursor, using a loop.

But that would probably be one of the worst examples of using a cursor. A better alternative might be to create a view returning the same data as your SP, but for all employees:

CREATE VIEW employees_compensation_view
AS
SELECT
  employee_code,
  currency_cd,
  SUM(comprate) AS salary
FROM employees_compensation
GROUP BY
  employee_code,
  currency_cd

You would then be able just to join the view to your query, like this:

SELECT
  your present columns,
  ecv.currency_cd,
  ecv.salary
FROM
  your present joins
  LEFT OUTER JOIN employees_compensation_view AS ecv
    ON b.employee_code = ecv.employee_code
;

For better encapsulation of your business logic, you could also change the stored procedure query like this:

SELECT
  currency_cd,
  salary
FROM employees_compensation_view
WHERE employee_code = @emp_code

That is, if you still needed that SP.