How about:

delete from mytable where Num1 = ?nValue and Num1 in
(select Num2 from MyTable where Num1 = ?nValue)

>Hi,
> I would like to delete each time two mutual records in the process.
>for example :
>mytable.dbf
>
>num1 num2
>11111 22222
>33333 44444
>22222 11111
>55555 66666
>77777 88888
>99999 00000
>
>means the 1st record and 3rd record should be deleted from the table,
>
>11111 22222
>22222 11111
>
>Any help in coding will be appreciated.
>PP