WWorkTools
DIAGNOSE → FIX

SQL NULL Comparison Returns No Rows

Equality operators do not treat NULL like a normal value.

LIKELY CAUSE

Why it happens

Use IS NULL / IS NOT NULL and understand three-valued logic.

SAFE FIX

What to do

Replace = NULL with IS NULL.

Debug in this order

  1. Reproduce the problem on the smallest sample that still fails.
  2. Inspect the exact keys, types, ranges or markup involved instead of only the displayed value.
  3. Fix the root cause, then rerun the original case and one known-good case.
  4. Document the rule if the same problem can return in recurring work.
WORKTOOLS RULE

Do not hide an unexplained data error with a cosmetic workaround. Make the input and matching logic predictable first.

Solution finderDescribe the task and get a matching tool or guide.Profile the dataCheck types, missing values and duplicates locally.Related guidesLearn the underlying pattern.