Connect to Oracle from ArcGIS—Help | ArcGIS for Desktop
Connect to a user-schema geodatabase or different version
You are connected to the DEFAULT version of the master sde geodatabase when you initially connect using the Database Connection dialog box. If you want to connect to a user-schema geodatabase, a transactional version other than DEFAULT, or an historical version, use the Geodatabase Connection Properties dialog box. Note that user-schema geodatabases are listed as transactional versions in this dialog box. For more information, see Connect to a specific geodatabase version
Connect to a specific geodatabase version—Help | ArcGIS for Desktop
You should really check all the Online available information first, before posting questions here.
