>thanks Edward your reply.
>I am not using sql related commands like update etc. I am using free tables with replasing command.
>thanks

It has nothing to do with SQL. Open your data in shared mode, and use buffering if users will edit data directly in grids. This case you should read in Help about TableUpdate,TableRevert,Cursorsetprop (these topics have code examples).
If users will not edit directly in grid, then you need to open data in shared mode, and nothing else.