IF UPDATE() in SQL server trigger

Question

If there's:

IF UPDATE (col1)

...in the SQL server trigger on a table, does it return true only if col1 has been changed or been updated?

I have a regular update query like

UPDATE table-name 
   SET col1 = 'x', 
       col2 =  'y' 
 WHERE id = 999

Now what my concern is if the "col1" was 'x' previously then again we updated it to 'x' would IF UPDATE ("col1") trigger return True or not?

I am facing this problem as my save query is generic for all columns, but when I add this condition it returns True even if it's not changed...So I am concerned what to do in this case if I want to add condition like that?

Answer 1

It returns true if a column was updated. An update means that the query has SET the value of the column. Whether the previous value was the same as the new value is largely irelevant.

UPDATE table SET col = col

it's an update.

UPDATE table SET col = 99

when the col already had value 99 also it's an update.