“<>” vs “NOT IN”

Question

I was debugging a stored procedure the other day and found some logic something like this:

SELECT something
FROM someTable
WHERE idcode <> (SELECT ids          


        

Answer 1

<> is essentially "nor"

on SQL WHERE NOT demo I tried the following

FAILS:

WHERE NOT Country='Mexico' AND WHERE NOT country ='Sweden'

WORKS

WHERE NOT Country='Mexico' AND country<>'Sweden'