You can check to see if the table exists in Oracle by executing the following SQL statement:
select *
from all_objects
where object_type in ('TABLE','VIEW')
and object_name = 'OBJECT_NAME';
For example, if you are looking for a suppliers table, you would execute:
select *
from all_objects
where object_type in ('TABLE','VIEW')
and object_name = 'SUPPLIERS';
For example, you may have executed the following SQL statement:
select *
from suppliers;
But the suppliers table is not owned by you, but rather, it is owned by a schema called app, you could fix your SQL as follows:
select *
from app.suppliers;
If you do not know what schema the suppliers table/view belongs to, you can execute the following SQL to find out:
select owner
from all_objects
where object_type in ('TABLE','VIEW')
and object_name = 'SUPPLIERS';
This will return the schema name who owns the suppliers table.