Question

There are two not equals operator – != and <>.

What’s the difference between them? I heard that != is more efficient than other for comparing strings. Could anyone give a qualitative comment on this statement.

Answer 1

They are the same (as is the third form, ^=).

Note, though, that they are still considered different from the point of view of the parser, that is a stored outline defined for a != won’t match <> or ^=.

This is unlike PostgreSQL where the parser treats != and <> yet on parsing stage, so you cannot overload != and <> to be different operators.