is (binary comparison)

1. Supports is not distinct from
2. Not for row-values

The not standardized binary is operator works in some SQL dialects like a null-safe comparison: It 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 c2

Note that this is not the same as the standardized unary is [not] null operator as it allows two arbitrary expressions to be compared.

Related

• Standardised version of this operator: IS NOT DISTINCT FROM (null-safe equals comparison)

• Tutorials:

  • NULL-Aware Comparison: is [not] distinct from (with further alternatives)

  • NULL: Indicating the Absence of Data

  • The Three-Valued Logic of SQL

Normative References

<=> is not defined in the SQL standard.