Hi,
Yes! it is possible to to create a mercator map that reads from an IDOC (output from SAP) and inserts it to a Sybase database and/or Oracle 8i.
For reading the IDoc from the SAP you need to use ALE adapter which will pull the Idoc from SAP and make it available as an input to the Mercator Input card & then you can do the processing on this data in your output card wherein you can specify where you want to have your output like would you like to put your output to a Sink, File, Databse etc.. there are many options available which you can find in the output card options.
In short in my opinion it is very much possible.
cheers,
Shrini.