要查看所有用户，您可以使用以下SQL查询：

SELECT u.usename AS username, u.usesysid AS user_id, u.usecreatedb AS create_database, u.usesuper AS is_superuser, ARRAY(SELECT n.nspname FROM pg_catalog.pg_namespace n WHERE n.nspowner = u.usesysid) AS user_schemas, pg_catalog.array_to_string(u.valuntil, ' ') AS password_expirationFROM pg_catalog.pg_user uORDER BY 1;

这将返回所有用户的用户名、用户ID、是否具有创建数据库权限、是否是超级用户、用户拥有的模式以及密码过期信息。