if you faces this error, check this 4 cases.

1. Database not connected.
2. Table not authorized.
3. Spelling error or indeed table does not exist.
4. Naming the owner in front of the table and SELECT.

Ex1)

- Reconnect to the database.

Ex2)

- Ask your DBA for permission.

Ex3)

- SELECT * FROM TABEL;
-> SELECT * FROM TABLE;

Ex4)

- SELECT * FROM owner.TABLE