When I asked a client for a copy of his database he sent me a .ctl file, it seems it is a control file of an Oracle database. I have no experience in Oracle, I'm a SQL Server guy. I have installed an Oracle XE 18 instance in a test server. What do I have to do to connect to this database an access the tables? Is it possible to do so only having this .ctl file or do I need more files?
A control file is a metadata file and lists some system configuration settings and all the datafiles and their paths. A typical file is quite small and does not contain any user data.
You need a datapump export or, even better, as suggested by Philᵀᴹ, an RMAN backup. The RMAN backup is preferable as you will not have to create users and tablespaces first which you would with an export.