>I have a database with several tables, the tables have principal indexes, but when I want to add a record with a key value that exist but is deleted,i can't because the key must be unique.How can I solve this problem ?

Don't recirculate keys is the best solution. AN alternative that gives some partial success is to embed a FOR clause in the index, but recreation of the index can be an issue, it will not be usable for Rushmore optimization, and should you ever try to recall a recirculated key or do not properly regulate reallocation of n out-of-sequence key in recirculation, you invite lots of trouble. You also create problems if you ever move from the native VFP file system, whose concept of records flagged as deleted but still present is not very portable.