I've been joining SDF3 files and SQL 2008 tables using Mapguide Studio with mixed results. The joins are not stable. I get a successful "test connection" with my SQL 2008 tables. I can see all the tables but fails on the SDF3<->SQL 2008 table joins. I made both joining fields integers with mixed results.
I made the joins using the FDO ODBC provider ... trying both connection types "database" and "DNS connections".
So my questions is three fold;
1) Who has made Mapguide 2010 and SLQ 2008 table joins successfully?
2) how many joins have you made?
3) and are you using mapguide 2010 in a production enviornment?
How are you doing? Sounds like you're experiencing similar frustrations to what I'm facing. From what I've been able to discover, the SQL 2008 Spatial FDO provider does not support SQL Views that are made by joining tables in SQL and it does not support Feature Joins created in Studio on SQL data connections.
I've updated the Autodesk SQL 2008 Spatial FDO provider with the latest OSGEO release. It solved some other issues with SQL 2008 data (namely MGE not recognizing UniqueIdentifier data types), but still no luck on the joins.
Here's an OSGEO post that might provide some clues. I haven't had time to go through it entirely yet, but I'm hoping that we may be able to come up with a workaround from some of this info. http://n2.nabble.com/SQL-Server-2008-views-and-fdo-again-td4273589.html#a4295305
At present, what we are doing is creating a new table that joins data from the required tables in SQL Server, creating a stored procedure that updates the new table on a regular basis (almost live) and then using that table in MGE.