Assuming your table of wages is indexed on employee you could populate a cursor, empl, with the name of employees whose wages you want summed by doing:
SELECT employee, SUM(wages) as total_wage ;
FROM wagetabl WHERE employee IN ;
(SELECT employee FROM empl ;
GROUP BY 1 ;
ORDER BY 1

In the future, please provide a more descriptive subject than "How to do this?"

>Using SQL may involve millions of records while there might be least then 10 items in my grid. I want the fastest way to get the same result.
>Your comment is welcome.
>BTW, it seems that there is no way to sum up a specific grid column with several keystrokes.