用循环向数据表中插入数据,为什么循环一次会插入两条相同的数据,最后一次循环插入一条数据???

Question

用循环向数据表中插入数据,为什么循环一次会插入两条相同的数据,最后一次循环插入一条数据???
begin
    booklist:=Form5.dbgrid1.SelectedRows;
    for i:=0 to booklist.Count-1 do
       begin
       Form5.adoquery1.Book:=booklist[i];
  
       FAuxQty:=Form5.DBGrid1.DataSource.DataSet.fieldbyname('订购数量').AsInteger;
       FBillNO:=Form5.DBGrid1.DataSource.DataSet.Fieldbyname('单据编号').AsString;
       adoquery1.Close;       adoquery1.SQL.Text:='insert into table1 (FAuxQty,FBillNo)'+ 
                           'values('''+inttostr(FAuxQty)+''','''+FBillNo+''')';
       adoquery1.ExecSQL;
       end;
end.

Answer 1

begin
    booklist:=Form5.dbgrid1.SelectedRows;
    for i:=0 to booklist.Count-1 do
       begin
       Form5.adoquery1.Book:=booklist[i];
  
       FAuxQty:=Form5.DBGrid1.DataSource.DataSet.fieldbyname('订购数量').AsInteger;
       FBillNO:=Form5.DBGrid1.DataSource.DataSet.Fieldbyname('单据编号').AsString;
       adoquery1.Close;       adoquery1.SQL.Text:='insert into table1 (FAuxQty,FBillNo)'+ 
                           'values('''+inttostr(FAuxQty)+''','''+FBillNo+''')';
       adoquery1.ExecSQL;       adoquery1.Open;
       adoquery1.Next; //指向下一条记录
       end;
end.

Answer 2

var bm:Tbook;
    count,i:integer;
begin
  bm:=getbook;
  count:=Form5.dbgrid1.SelectedRows.Count;
  if count >0 then
  for i:=0 to count - 1 do
  begin
    bm:=pointer(Form5.dbgrid1.SelectedRows.items[i]);
    gotobook(bm);
    //或者 gotobook( pointer(Form5.dbgrid1.SelectedRows.items[i])  
       FAuxQty:=Form5.DBGrid1.DataSource.DataSet.fieldbyname('订购数量').AsInteger;
       FBillNO:=Form5.DBGrid1.DataSource.DataSet.Fieldbyname('单据编号').AsString;
       adoquery1.Close;       adoquery1.SQL.Text:='insert into table1 (FAuxQty,FBillNo)'+ 
                           'values('''+inttostr(FAuxQty)+''','''+FBillNo+''')';
       adoquery1.ExecSQL;
       end;
end.