SQL: How to perform string does not equal

Question

I have the following query

SELECT * FROM table
WHERE tester <> \'username\';

I am expecting this to return all the results where test

Answer 1

Your where clause will return all rows where tester does not match username AND where tester is not null.

If you want to include NULLs, try:

where tester <> 'username' or tester is null

If you are looking for strings that do not contain the word "username" as a substring, then like can be used:

where tester not like '%username%'