default:
nulls not distinct
BigQuery
Db2 (LUW)
MariaDB
MySQL
Oracle DB
PostgreSQL
SQL Server
SQLite
2007
2009
2011
2013
2015
2017
2019
2021
✓ 2008R2 - 2022
⚠ 11gR1 - 21c
a
If some but not all constraint columns are
null