Drop procedure if exists

BigQueryDb2 (LUW)MariaDBMySQLOracle DBPostgreSQLSQL ServerSQLite200520072009201120132015201720192021✓ 2017+✓ 11+⊘ 11gR1 - 21c✓ 5.0+✓ 5.1+⊘ 11.1 - 11.5.7✓ 2.0+