You cannot always duplicate not like patterns with like and the negative wildcard character [^]. Match strings with negative wildcard characters are evaluated in steps, one character at a time. If the match fails at any point in the evaluation, it is eliminated.
For example, this query finds the system tables in a database that have names beginning with “sys”:
select name from sysobjects where name like "sys%"
If you have a total of 32 objects and like finds 13 names that match the pattern, not like finds the 19 objects that do not match the pattern.
where name not like "sys%"
However, this pattern may produce different results:
like [^s][^y][^s]%
Instead of 19, you might get only 14, with all the names that begin with “s” or have “y” as the second letter or have “s” as the third letter eliminated from the results, as well as the system table names.