How to flip bit fields in TSQL

Question

I'm trying to flip a bit field in SQL Server using an update query, that is, I want to make all the 0's into 1's and vice versa. What's the most elegant solution?

There doesn't seem to be a bitwise NOT operator in TSQL (unless I'm missing something obvious) and I haven't been able to find any other way of performing the update.

Answer 1

I was pretty sure that most SQL flavors had a bitwise NOT, so I checked and there does appear to be one in TSQL.

Answer 2

here's a few ways described http://johnnycoder.com/blog/2006/10/04/t-sql-tip-flip-bit/

Answer 3

You don't need a bitwise-not for this -- just XOR it with 1 / true.

To check it:

select idColumn, bitFieldY, bitFieldY ^ 1 as Toggled
from tableX

To update:

update tableX
set bitFieldY = bitFieldY ^ 1
where ...

MSDN T-SQL Exclusive-OR (^)

Answer 4

UPDATE tblTest SET MyBitField = CASE WHEN MyBitField = 1 THEN 0 ELSE 1 END

It's bland but everyone will understand what it's doing.

EDIT:

You might also need to account for nulls as suggested in the comments. Depends on your req's of course.

UPDATE tblTest SET 
   MyBitField = CASE 
      WHEN MyBitField = 1 THEN 0 
      WHEN MyBitField = 0 THEN 1
      ELSE NULL -- or 1 or 0 depending on requirements
   END

Answer 5

Did you try this?

UPDATE mytable SET somecolumn = 
  CASE WHEN somecolumn = 0 THEN 1 
       WHEN somecolumn IS NULL THEN NULL
       WHEN somecolumn = 1 THEN 0
  END

Answer 6

Why not a simple bitfield = 1 - bitfield?