>I have the code below:
>
> close data
> do backup.prg
>
>But suppose that my table is still open in a network
>I don't remember which is the command to check if table is in use

You can try to get an exclusive hold on the data like so:

ErrCode = 0
ON ERROR ERRCODE = 1
OPEN DATA <your dbc name here> EXCLUSIVE
if ERRCODE=1
 =MessageBox("File access is denied.")
else
 close data
 do backup.prg
endif

Yelena