Postgresql删除指定的数据库，一直显示有会话在使用，如何解决

select pg_terminate_backend(pg_stat_activity.pid) from pg_stat_activity where datname = '数据库名称' and pid <> pg_backend_pid();

SELECT CAST(pg_terminate_backend(pid) AS VARCHAR(10)) FROM pg_stat_activity WHERE datname='数据库名称';