Question

I’m doing a relatively simple mysql query:

         SELECT g.id FROM myTable g
            WHERE g.timestamp > '0' 
            AND g.userId = '1'
            AND g.foo != '34'
            ORDER BY g.id DESC LIMIT 0, 10

This query returns 0 rows, however if I remove the last condition, i.e change it to:

         SELECT g.id FROM myTable g
            WHERE g.timestamp > '0' 
            AND g.userId = '1'
            ORDER BY g.id DESC LIMIT 0, 10

That returns 5-6 rows. This is very strange to me, since in all of those rows, the int column foo is set to NULL

What am I doing wrong?

Answer 1

Comparing something wilh NULL will result in unknown. That is why NULL values have to be compared with the IS operator.

Replace

AND g.repostVia != '34'

with

AND (g.repostVia != '34' or g.repostVia  is null)

or use the NULL-safe equality operator (thanks to eggyal):

AND NOT g.repostVia <=> '34'