ColdFusion uses Boolean logic to handle conditional expressions. Proper handling of NULL values requires the use of ternary logic. The IS [NOT] NULL clause works correctly in ColdFusion. However the following expressions do not work properly when the column breed is NULL:
WHERE (breed > 'A') WHERE NOT (breed > 'A')
The correct behavior should not include NULL breed columns in the result set of either expression. To avoid this limitation, you can add an explicit rule to the conditionals and rewrite them in the following forms:
WHERE breed IS NOT NULL AND (breed > 'A') WHERE breed IS NOT NULL AND not (breed > 'A')