Query MDG tables via SAP Studio

An answer to your question is a big “YES”. You can execute queries against the tables either if you are using an ABAP program or also you can execute these queries from native SQL environment.

For E.g.

DATA: lt_TBL LIKE TABLE OF KNA1.
SELECT * from KNA1 INTO lt_TBL up to 5 rows.

The snippet above lets you get the 5 rows from table KNA1 table and store in an internal table for further use.