sql negation operators : != vs <>

Question

Why are there two negation operators in SQL language? != and <>.

Are they redundant or is there a difference between them depending on operands ?

Which one should I use to negate strings in MySQL ?

score 5 · Accepted Answer · edited Dec 12 '15 at 12:28

5

<> is ISO Sql Standard
!= is vendor specific

They both have no difference among them. It is just a personal preference which one to use. I always prefer <> since it is a ISO SQL standard

edited Dec 12 '15 at 12:28

Mark Rotteveel

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answered Dec 12 '15 at 12:26

Pரதீப்

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Mark Rotteveel · Answer 2 · 2015-12-12T14:08:57.873

2

The SQL standard only specifies <> for not equals. SQL:2011 Foundation, section 5.2 <token> and <separator> specifies:

<not equals operator> ::=
  <>

However some SQL implementations (like MySQL) also support != as a lot of programmers are more familiar with != for not equals. They are fully equivalent, so you can use either, but from a standards point of view you should use <>.

See also the MySQL documentation for not equals.

edited Dec 12 '15 at 14:08

answered Dec 12 '15 at 12:27

Mark Rotteveel

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I wouldn't say "most SQL implementations also support `!=`, but there is no reason for a downvote on this answer. – Gordon Linoff Dec 12 '15 at 12:43
@gordonlinoff I replaced it with some; I can't recall seeing one that didn't support it, but as I haven't seen all SQL implementations, most is likely not correct. Thanks. – Mark Rotteveel Dec 12 '15 at 14:10

sql negation operators : != vs <>

2 Answers2