Hi,
Thanks for your help the other time.It really helped a lot.Now I face another problem.I created a set of tables in a database.What happened next was,and error message states that there is no back links to the database.So I re checked and find that nothing is wrong.I tried using

OPEN MyDatabase EXCLUSIVE
VALIDATE DATABASE RECOVER
Then I was prompted again that I must use the database exclusive.I don't really know what to do next.So I removed the tables from the database and created a new table.The same thing happened again.

Your help is very much appreciated as I am still a new user to VFP.