SQL fundamental question '!=' vs '<>' vs 'Not' [duplicate]

This question already has answers here: Closed 12 years ago.

Possible Duplicate:

Testing for inequality in T-SQL

Hi,

does there any different to use the '!=' vs '<>' vs 'Not'?

which one will have the worst perfor开发者_JS百科mance

or it exist just because of the backward compatibility syntax?

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• NOT does not always act the same
• != or <> are identical, no deprecation mentioned. <> is ISO though

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AFAIK, if you want to check for NULL, you must use IS NOT and not != or <>