What are the opportunities for converting databases, for example, can I convert another SQL Server database to Oracle server database?
Just use Oracle Data Pump Wizard. It allows you to convert any local or remote ADO-compatible database (i.e. any database for which you have an OLE DB Provider or ODBC driver), including its structure and data with full customization of the target Oracle database. You can create a new Oracle database or even convert your source tables and their data to the existing Oracle database, select objects for conversion and adjust their properties for the target database.