NULL values in where clause

Question

i\'ve got a table \"bla\" like this:

[id]    [name]    [fk]
1       test      4
2       foo       5
3       bar       NULL

if i do the sql

Answer 1

NULL doesn't compare equal to anything. You'll need to accept nulls explicitly:

where fk <> 4 or fk is null;

See Working with NULL for more information about NULL handling.