What does “<>” mean in Oracle

Question

What does <> mean in SQL language: Sample code is as follows

SELECT ordid,
       prodid,
       qty
FROM   item
WHERE  prodid IN (SELECT prodid
                  


        

Answer 1

I'm surprised nobody mentioned the null special case. I think the meaning of <> is more something like

has a value which is not equal to

In this case it filters out items which have ordid 605 and items which have a null ordid.

It may be obvious in this context that ordid is never null, but it is never hurts to remember that null is not <> from 605 (or from anything).