>I getting data directoly not using cursor i try:
><>
>SELECT exam
>If obt01>=min01
> =MESSAGEBOX("check column4 box,if empty")
> RETURN =.t.
>ENDIF

If it's for first 10 records only then it should be like this:

select top 10 [order_field],obt01,min01 from exam ;
  into cursor mycursor nofilter order by 1
select mycursor
locate for obt01>=min01
if found()
  =MESSAGEBOX("check column4 box,if empty")
endif