Comparing with NULL is always FALSE

[petriq]

Library name and version

• Kros.KORM 6.2.0

Description

KORM fails to parse correct condition for NULL comparison.

Steps To Reproduce

Example:

var test = _database.Query<MovementsOverviewSearchResult>()
                .Where(x => x.PartnerName != null);

Expected behavior

LINQ query above should be parsed

SELECT ... FROM ... Where (PartnerName IS NOT NULL)

Actual behavior

KORM parses the query as

SELECT ... FROM ... Where (PartnerName <> NULL)

Comparing NULL with anything using operators =, !=, <> ALWAYS produces FALSE. Even NULL = NULL is FALSE. Therefore, IS and IS NOT keywords should be parsed instead when comparing with NULL.