Question : SQL <>

I am trying to select records where the 3 and forth characters are not equal to N7

Here is my code.
WHERE (LEFT(RIGHT(_Code, 3), 2) <> 'N7'  OR LEFT(RIGHT(_Code, 3), 2)  <>'N8')

It does not work.

I tested
WHERE (LEFT(RIGHT(_Code, 3), 2) <> 'N7' ) and It works.

Why can I not put the N7 and N8 condition next to each other?

Answer : SQL <>

You need to use AND, not OR. One of both conditions is true if the other is false ...