there are no such things you can imp or exp from one database system to another vice versas. what you can do is to use Oracle migration workbench to convert data from SQL to Oracle and I don't know the other way.
If you just want a minimum effort method, I would sugest using ODBC to transfer the data - unless this is a regular, high volume data transfer of course.
I guess that most of mainly RDBMS will have a tool to migrate data from Oracle.
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