Does hibernate convert column != null in HQL to a column is null in SQL?
That is a binary operator in hibernate you should use
is not null
Have a look at 14.10. Expressions
If you do want to use null values with '=' or '<>' operators you may find the
answer from @egallardo hier
very useful.
Short example for '=': The expression
WHERE t.field = :param
you refactor like this
WHERE ((:param is null and t.field is null) or t.field = :param)
Now you can set the parameter param either to some non-null value or to null:
query.setParameter("param", "Hello World"); // Works
query.setParameter("param", null); // Works also
No. You have to use is null and is not null in HQL.
No. See also this link Handle conditional null in HQL for tips and tricks on how to handle comparisons with both null and non-null values.