How can we add security to our data?
>Is there a way to give a table a security when it has been illegaly copied from a computer?
>
>Like for example, a person installs vfp from his machine and copied a table and edits its record, is there a way to prevent him from editing the records?

Not really. DBFs by their very nature, as desktop database/tables, are not secure. Anyone can open them with other programs, like Excel, or through ODBC or OleDB, or even a text editor.

If you want real security, you'd have to upsize your database to something like SQL Server or similar.

What you can do, if you want to stay with DBFs, is to encrypt the data.

You can use commercial products, like Cryptor, or do your own encryption using the Windows CryptoAPI. This one is free, and included in Windows. From VFP7+ you have a class in the FFC (_crypt.vcx) that shows you examples on how to do that. You can find and run them through the Component Gallery with DO (_gallery) or through the new task Pane.

For more samples you can see my article in CoDe Magazine, (reposted with permission at: http://feldstein.net/CodeCryptoArticle.htm)