I have been asked to estimate the time to modify an existing VFP6 app to run SQL queries against Oracles tables rather than VFP tables.

For the most part this should be no big deal. I'm concerned, however, that the app has numerous multiselect pick-lists where the users often will choose as many as 500 of something. If the picklists are converted to SELECT ... WHERE field IN ('XXX','YYYY','ZZZ'), then you can on only have a defined limit (maybe 255) to the number of selected items. Also, the SELECT IN approach slows down noticeably once the number of items gets above about 20 or somethings

In the pure VFP environment, the pick-lists currently are saved to a table and then the SQL query only needs to join the pick-list table to one of the main tables.

Once a VFP application is a front-end tool to Oracle, will the queries keep running efficiently with the main tables in Oracle and the picklist file prepared and saved locally? Otherwise, how can I update Oracle with the temporary pick-list table before running the query

Thanks,