IS NOT DISTINCT FROM (null-safe equals comparison)

1. Supports the non-standard spaceship operator instead: <=>
2. Supports the non-standard binary is operator instead
3. Not for row-values

The equals comparison (=) returns unknown if one of the compared values is the null value. Is not distinct from is similar to = but never returns unknown. Instead it returns false if only one argument is null or true if both arguments are null.

SELECT …
  FROM …
 WHERE c1 IS NOT DISTINCT FROM c2

Related

• Negation: IS DISTINCT FROM (null-safe not equals comparison)

• Tutorials:

  • NULL-Aware Comparison: is [not] distinct from

  • NULL: Indicating the Absence of Data

  • The Three-Valued Logic of SQL

Normative References

Is not distinct from is defined in ISO/IEC 9075-2:2023 as the optional feature T152, “DISTINCT predicate with negation”.