ADO操作数据库

1、连接Excel

procedure TForm1.ConnectToExcel(EFileName: string); 
var 
    strConn: widestring;
    str:TStrings;
    i:Integer;
begin 
    str:=TStringList.Create;

    //表形式，第一行为列名
    strConn := 'Provider=Microsoft.Jet.OLEDB.4.0;' 
        + 'Data Source=' + EFileName + ';' + 
        'Extended Properties=IMEX=1;Excel 8.0;HDR=false;Persist Security Info=False'; 

    //标题头为第一行的值，标题为F1，F2....
   { strConn := 'Provider=Microsoft.Jet.OLEDB.4.0;'
        + 'Data Source=' + EFileName + ';' +
        'Extended Properties=IMEX=1;Excel 8.0;Mode=Read;HDR=NO;Persist Security Info=False';  } 

    AdoConnection1.Connected := False;
    AdoConnection1.ConnectionString := strConn;
    try 
        AdoConnection1.Connected:=true;
        AdoConnection1.GetTableNames(str, True);
    except 
        ShowMessage('不能连接到给定的Excel文件确认给定的 '); 
        raise; 
    end; 

    with AdoQuery1 do 
    begin 
        Close;
        Sql.Clear;
        Sql.Text:='select   *   from   [机民井调查表$]'; //表为为Sheet名称 
        Open;
    end; 
end;

2、ADOQuery查看字段类型

     //得取某字段类型
     case ADOQuery1.FieldByName(FieldName).DataType of
          ftString, ftMemo, ftFmtMemo,
          ftFixedChar, ftWideString:
          begin
              pType:='字符型';
          end;
          ftSmallint, ftInteger, ftWord,
            ftAutoInc, ftLargeInt, ftArray:
          begin
              pType:='整型';
          end;
          ftFloat, ftCurrency, ftBCD:
          begin
              pType :='浮点型';
          end;
          ftDate, ftDateTime:
          begin
              pType:='期日型';
          end;
      end;


      //所有字段类型
        TFieldType = (ftUnknown, ftString, ftSmallint, ftInteger, ftWord,
      ftBoolean, ftFloat, ftCurrency, ftBCD, ftDate, ftTime, ftDateTime,
      ftBytes, ftVarBytes, ftAutoInc, ftBlob, ftMemo, ftGraphic, ftFmtMemo,
      ftParadoxOle, ftDBaseOle, ftTypedBinary, ftCursor, ftFixedChar, ftWideString,
      ftLargeint, ftADT, ftArray, ftReference, ftDataSet, ftOraBlob, ftOraClob,
      ftVariant, ftInterface, ftIDispatch, ftGuid, ftTimeStamp, ftFMTBcd);

3、UDL文件的使用

ADOConnection1.ConnectionString:= 'FILE NAME=' + ExtractFilePath(Application.ExeName); + 'Data\data.udl';

4、插入、读取图片文件到数据库

    4.1、读取图片到Image控件

//uses jpeg
var
    MS: TMemoryStream;
    JpegImage:TJpegImage;
begin
    try
        MS := TMemoryStream.Create;
        TBlobField(ADOQuery1.FieldByName('img')).SaveToStream(MS);
        MS.Position := 0;
        JpegImage := TJpegImage.Create;
        JpegImage.LoadFromStream(MS);
        Image1.Picture.Graphic := JPegImage;
    finally
        JpegImage.Free;
        MS.Free;
    end;
end;

    4.2、插入图片

//jpeg
TBlobField(AODQuery1.FieldByName('img')).Assign(Image1.Picture.Graphic);