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把excel表中的数据导入数据库，出现无效索引字样。是什么原因？procedure TFrm_Fengmian.SpeedButton3Click(Sender: TObject);
var i,j:integer;
str,Sqlstr,Datestr:string;
year,month,day:word;
begin
   ExcelWorkbook1.ConnectTo(ExcelApplication1.Workbooks[1]);
  ExcelWorksheet1.ConnectTo(ExcelWorkbook1.Worksheets[1] as _Worksheet);//Excelworksheet1与Excelworkbook1建立连接  //decodedate(DateTimePicker3.DateTime,year,month,day);
  //Datestr:=inttostr(year)+'-'+inttostr(month);
  while ADOQuery1.RecordCount<>0 do
  begin
    ADOQuery1.First;
    ADOQuery1.Delete;
  end;
  ADOQuery1.Active:=false;
  ADOQuery1.SQL.Clear;  Sqlstr:='Select * from shujubiao';
  ADOQuery1.SQL.Add(Sqlstr);
  ADOQuery1.Active:=true;
  i:=2;
  while trim(excelworksheet1.cells.item[i,1])<>'' do
  begin
    ADOQuery1.Insert;
       //decodedate(DateTimePicker3.DateTime,year,month,day);
       //Datestr:=inttostr(year)+'-'+inttostr(month);
    ADOQuery1.fieldbyname('名称').AsString:=ExcelWorksheet1.Cells.Item[i,1];
    ADOQuery1.fieldbyname('型号').AsString:=ExcelWorksheet1.Cells.Item[i,2];
    ADOQuery1.fieldbyname('产品编号').AsString:=ExcelWorksheet1.Cells.Item[i,3];
    ADOQuery1.fieldbyname('合格证号').AsString:=ExcelWorksheet1.Cells.Item[i,4];
    ADOQuery1.fieldbyname('设备编码').AsString:=ExcelWorksheet1.Cells.Item[i,5];
    ADOQuery1.fieldbyname('安装地点').AsString:=ExcelWorksheet1.Cells.Item[i,6];
    ADOQuery1.fieldbyname('安装单位').AsString:=ExcelWorksheet1.Cells.Item[i,7];
    ADOQuery1.fieldbyname('安装日期').AsDateTime:=strtodate(ExcelWorksheet1.Cells.Item[i,8]);
     ADOQuery1.fieldbyname('投产日期').AsDateTime:=strtodate(ExcelWorksheet1.Cells.Item[i,9]);
    ADOQuery1.fieldbyname('企业名称').AsString:=ExcelWorksheet1.Cells.Item[i,10];    ADOQuery1.Post;
    i:=i+1;
 end;
  showmessage('数据入库成功！');