用循环语句
dbgrid1.datasource.dataset.open;
dbgrid1.datasource.dataset.last;
s:=dbgrid1.datasource.dataset.fieldvalue['df'];
dbgrid1.datasource.dataset.first;
i:=dbgrid1.datasource.dataset.recordcount;
for j:=0 to i-2 do
begin
s1:=dbgrid1.datasource.dataset.fieldvalue['df'];
与s比较
dbgrid1.datasource.dataset.next;
end;