Null Value
Definition
A null value indicates missing or unknown information in a database.
A special database marker for missing, unknown, or not applicable information that is not identical to null or empty text.
Simply explained
An unknown delivery date is neither the number zero nor an empty word, but explicitly unknown.
Why it matters in practice
Helps develop and operate digital systems robustly, securely, and maintainably.
Example from business
An unknown delivery date remains NULL instead of being stored as 0 or an empty string.
Limits and pitfalls
- Equating NULL with 0 or performing comparisons with = instead of IS NULL.
Origin & history
NULL and three-valued logic are components of relational SQL systems.
Use in mid-sized companies
- Possible application: An unknown delivery date remains NULL instead of being stored as 0 or an empty string.
Frequently asked questions
What does null value mean?
A special database marker for missing, unknown, or not applicable information that is not identical to null or empty text.
Which mistakes should be avoided?
Equating NULL with 0 or performing comparisons with = instead of IS NULL.
Sources
Source checked on 10.10.2026. Editorial application examples are hypothetical; no evidence of real customer results.
Editorially reviewed on: