query “not equal” doesn't work

Question

I have very simple query like this:

SELECT * FROM `all_conversations` WHERE `deleted_1` != \'1\';

And my deleted_1 be default

Answer 1

SELECT * FROM all_conversations WHERE deleted_1 <> 1 OR deleted_1 IS NULL

NULL values need special treatment: http://dev.mysql.com/doc/refman/5.1/en/working-with-null.html

I'd suggest using the diamond operator (<>) in favor of != as the first one is valid SQL and the second one is a MySQL addition.