Here is some handy TSQL to determine all the FK relationships in a database. The basic ideas is we can use this meta data to automatically determine if a form should have a Combo Box rendered instead of a textbox.
-- List all Foreign key Relationships in User Tables
SELECT so.name as ForeignTableName, sc.name as ColumnName,
s.name + '.' + PKT.name as PrimaryTableName
from sysreferences r
inner join sysconstraints c on r.constid = c.constid
inner join sys.tables pkt on PKT.object_id = r.rkeyid
inner join sys.columns sc on sc.column_id = r.fkey1 and r.fkeyid = sc.object_id
inner join sys.schemas s on s.schema_id=pkt.schema_id
inner join sys.tables so on r.fkeyid = so.object_id
where so.is_ms_shipped=0
order by so.name, sc.name
