How can Oracle check all tables under a user?

You can use the following SQL query to view all the tables under a user in an Oracle database:

SELECT table_name FROM all_tables WHERE owner = '用户名';

Please replace ‘username’ with the specific name of the user you want to query. This query will return all table names under the specified user.

Additionally, if you are a database administrator (DBA) or a user with sufficient permissions, you can also use the following SQL query to view all tables, including system tables:

SELECT table_name FROM all_tables;

Before executing these queries, make sure you are connected to the correct database instance and have sufficient permissions to access the relevant table information.