If Statement Using Select Update Set?

If EXISTS(Select col_Num From table1 Where col_Num = '101')
Begin
    Update table1 SET col_Bit = 'True'
End
Else
Begin
    Update table1 SET col_Bit = 'False'
End

Update table1
SET col_Bit = CASE WHEN col_Num = '101' THEN 1 ELSE 0 END

[SQL bit-type columns use 0/1, not 'true'/'false' (nor 0/-1).]

I don't know what to think because my table clearly has True or False in the Bit type column.

Thanks I'll try your advice and get back to you....

Problem:

Both examples set 'every row' in the bit column to True, the back to False when I run the code again.

The row with matching '101' data is set as well as every row in the table...

are u using SQL server 6.5 or 7.0, I found the similar problems on these versions

update table1
   set col_Bit = case when col_Num = '101' then 1 else 0 end

(1) You're right... bits show as "True" or "False" in the grid display, but they're stored as 1 or 0, and those are the values you must use to update a bit column.
(2) The above statement updates the col_Bit to True (1) if the same row has a col_Num of 101, otherwise it sets col_Bit to False (0).

I just noticed... this is the same as Scott Pletcher's solution.  Use 1 and 0 (not "true" and "false") and I think you'll see that it works just fine.

It still makes changes on all the other rows in the table.

I just want to flip-flop (toggle) one row.

You need to give us a predicate for the where clause on the update statement to restrict it to one row.