Question

I am fairly new to the more advanced database features, such as functions, but I was curious how you would do this in MSSQL (or if it is possible even):

If I have a table and the structure is something like this:

t_test

USR_VALUE   MULTIPLIER   TOLERANCE  VALUE_OK
100         .8           85         OK           
100         .9           85         NO

How would I get VALUE_OK to automatically update itself every time the row is updated depending on the USR_VALUE, MULTIPLIER and TOLERANCE (IE simple calculation:
(t_test.USR_VALUE * t_test.MULTIPLIER >= TOLERENCE)? "OK" : "NO")

Answer 1

You want the expression:

CASE
  WHEN USR_VALUE * MULTIPLIER >= TOLERANCE THEN 'OK'
  ELSE 'NO'
END

Note that you can add this to the table as a computed column using…

ALTER TABLE yourtable
ADD VALUE_OK AS     CASE
                      WHEN USR_VALUE * MULTIPLIER >= TOLERANCE THEN 'OK'
                      ELSE 'NO'
                    END

…but be wary of using this value in a WHERE clause where the cost of performing the calculation and lack of index may be prohibitive. Search for indexed calculated columns if you want to take this to the next level.