Self-referencing merge

BigQueryDb2 (LUW)MariaDBMySQLOracle DBPostgreSQLSQL ServerSQLite200520072009201120132015201720192021✓ 2008R2+a✓ 11gR1+a✓ 9.7+a✓ 2.0+a
  1. Syntax accepted, functionality not tested thoroughly
  2. Doesn’t support merge at all