MDB2 DSN documentation states that:
option: Additional connection options in URI query string format. options get separated by &.
The string format of the supplied DSN is in its fullest form:
phptype(dbsyntax)://username:password@protocol+hostspec/database?option=value
So the options should be passed as
sqlsrv://username@server:password@server.database.windows.net:1433/mydatabase?MultipleActiveResultSets=false
Unfortunately looking at MDB2 sqlsrv.php code, the _doConnect()
function doesn't appear to take any other options except for host, username, password and database. So it may not be possible to disable MARS when connecting.
For additional information about the 2.5 beta version of MDB2 see this answer.