>Hi,
> The previous case was settle. However, here come a new case. My program is excuting a certain process with 2ndtable. However, user may go to my listbox to add new record at the same time. Then, the operation interrupted. How could i keep the operation keep running and also can let user add new record in 3rdtable? Thank you

I don't quite understand. VFP is not multi-threaded, if you start some process you should wait until it's over. Or you run some query asynchronously on RDBMS back-end?