Checking database for NULL boolean value

Question

I have a field in a table that is boolean, a range of records have no value (not true or false). How do I write my SQL statement to find these?

I have tried the following SQL statements without success:

1) SELECT * FROM table WHERE field = NULL
2) SELECT * FROM table WHERE field != TRUE AND field != FALSE

Any help would be greatly appreciated.

Many Thanks, Ben

Solution 1

In TSQL, you need to use IS rather than = when comparing with NULL:

SELECT * FROM table WHERE field IS NULL

Solution 2

Try

select * from table where field IS null

Solution 3

You want IS NULL I believe:

SELECT * FROM table WHERE field IS NULL