Vienna Advantage Framework uses json Ajax request to fetch and send data to server. Ajax use MVC controller and MVC controller further use http://ADO.Net component to run database queries.
On Server Side database query execution, Vienna Framework provides function in DB Class.
DB.ExecuteReader(sql, parameter);
DB.ExecuteDataSet(sql, parameter);
DB.ExecuteDataScalar(sql, parameter);
DB.ExecuteQuery(string sql)