Why does the field type of an index matter?
Details such as your Crystal version, data types, how you are creating the query are all omitted.
A one line posting generally results in numerous posts, try providing the basics up front.
The way that most end up using disparate data is by creating Links (not imports) to the disparate databases from within MS Access, and then provide a Query in Access as the report datasource.
You'll find it a good deal faster than Crystal.
I've seen SQL Server->Oracle and DB2 in a Link Server environment working.
-k