Exactly what you need to do depends on the location of the two databases, and the server types.
You imply both databases are SQL Server, which makes it easier. If they are on the same server it's easier. If they have the same login details (or no login required) then it's easier again.
If those assumptions are true then this should work:
VB Code:
Public gConnection as String
...
combo1.additem "BBE"
combo1.additem "other database"
...
gConnection = "Provider=MSDASQL.1;Persist Security Info=False;Extended Properties=Description=LSSCE;DRIVER=SQL Server;SERVER=SONAMG\BBE;UID=sa;APP=Visual Basic;WSID=SONAMG;DATABASE=" & combo1.text & ";Network=DBMSLPCN"