Question

我使用adodb / dbgo进行编程并尝试使用此代码：

procedure TfrMain.dbeNoMejaKeyPress(Sender: TObject; var Key: Char);
begin
  dmWarbam.TblTrans_temp.Filtered := False;
  dmWarbam.TblTrans_temp.Filter := 'ID_ITEM = ' + QuotedStr(dbeNoMeja.Text);
  dmWarbam.TblTrans_temp.Filtered := True;
end;

和

procedure TfrMain.dbeNoMejaChange(Sender: TObject);
begin
  dmWarbam.TblTrans_temp.Filtered := False;
  dmWarbam.TblTrans_temp.Filter := 'ID_ITEM = ' + QuotedStr(dbeNoMeja.Text);
  dmWarbam.TblTrans_temp.Filtered := True;
end;

但以上都不能正常工作，当我在dbeNoMeja上按键时它没有过滤，而是将数据集插入到数据库中。

有人可以给我一些工作的例子（完整代码）

Answer 1

如果dbedit连接到与您要过滤的表相同的表，则会出现问题，因为一旦开始输入文本，表就会进入dsEdit状态。

使用普通的TEdit，并将通配符（*）附加到过滤器

中的字符串

dmWarbam.TblTrans_temp.Filter := 'ID_ITEM = ' + QuotedStr(edtNoMeja.Text+'*');

Answer 2

从Delphi-Neftalí改编的代码示例。很好，很简单！

procedure TForm1.Edit1Change(Sender: TObject);
begin

  // incremental search
  ClientDataSet1.Locate('FirstName', Edit1.Text, [loCaseInsensitive, loPartialKey]);
  Exit;

  // actual data filtering
  if (Edit1.Text = '') then begin
    ClientDataSet1.Filtered := False;
    ClientDataSet1.Filter := '';
  end
  else begin
    ClientDataSet1.Filter := 'FirstName >= ' + QuotedStr(Edit1.Text);
    ClientDataSet1.Filtered := True;
  end;

end;

将ClientDataSet的提供程序设置为ADO DB（在您的情况下）：

  Path := ExtractFilePath(Application.ExeName) + 'Data.MDB';
  // Exist the MDB?
  if FileExists(path) then begin
    ClientDataSet1.ProviderName := 'DSProvider';
    ADOQ.Open;
    ClientDataSet1.Active := True;
    ADOQ.Close;
    ClientDataSet1.ProviderName := '';
    lbldata.Caption := ExtractFileName(path);
    Exit;
  end;

Answer 3

我在Expert Exchange中找到了一个很好的解决方案，

unit dbg_filter_u;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Grids, DBGrids, DBTables, Db, StdCtrls;

type
  TForm1 = class(TForm)
    Table1: TTable;
    DataSource1: TDataSource;
    Query1: TQuery;
    DBGrid1: TDBGrid;
    cbFilterBox: TComboBox;        //a hidden combobox (Style = csDropDownList)
    procedure Table1AfterOpen(DataSet: TDataSet);
    procedure Table1AfterPost(DataSet: TDataSet);
    procedure DBGrid1TitleClick(Column: TColumn);
    procedure cbFilterBoxChange(Sender: TObject);
    procedure cbFilterBoxClick(Sender: TObject);
    procedure cbFilterBoxExit(Sender: TObject);
  private
    Procedure FillPickLists(ADBGrid : TDBGrid);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

//For Accessing some Protected Methods
type TCDBGrid = class(TCustomDBGrid);

//Storing the Values into the Picklist-Propertys of the asscociated Columns,
//this may cost time depending on the amount of the dataset
Procedure TForm1.FillPickLists(ADBGrid : TDBGrid);
const
  SQL_Text = 'Select Distinct %s From %s';
var
  q : TQuery;
  i : integer;
Begin
  If (Assigned(ADBGrid)) and
     (Assigned(ADBGrid.Datasource)) and
     (Assigned(ADBGrid.Datasource.DataSet)) Then
  Begin
    If (ADBGrid.Datasource.DataSet is ttable) Then
    begin
      q := TQuery.Create(self);
      try
        try
          q.DatabaseName := TTable(ADBGrid.Datasource.DataSet).DataBaseName;
          for i := 0 to ADBGrid.Columns.Count - 1 do  //for each column
          begin
            if ADBGrid.Columns[i].Field.FieldKind = fkData then  //only physical fields
            begin
              ADBGrid.Columns[i].ButtonStyle := cbsNone;  //avoid button-showing
              ADBGrid.Columns[i].PickList.Clear;
              q.Close;
              q.SQL.text := Format(SQL_Text,[ADBGrid.Columns[i].Field.FieldName,TTable(ADBGrid.Datasource.DataSet).TableName]);
              q.Open;
              While not q.eof do
              begin
                ADBGrid.Columns[i].PickList.Add(q.Fields[0].AsString);
                q.next;
              end;
              q.close;
            end;
          end;
        finally
          q.free;
        end;
      except
        raise;
      end;
    end else
      Raise exception.Create('This Version works only for TTables');
  end else
    Raise Exception.Create('Grid not properly Assigned');
end;

//Initial-Fill
procedure TForm1.Table1AfterOpen(DataSet: TDataSet);
begin
  FillPickLists(DBGrid1);
end;

//Refill after a change
procedure TForm1.Table1AfterPost(DataSet: TDataSet);
begin
  FillPickLists(DBGrid1);
end;


//Show a Dropdownbox for selecting, instead the title on Titleclick
procedure TForm1.DBGrid1TitleClick(Column: TColumn);
var
  ARect : Trect;
  DummyTC : TColumn;
begin
  If column.PickList.Count > 0 then
  begin
    cbFilterbox.Items.Assign(column.PickList);
    ARect := TCDBGrid(Column.Grid).CalcTitleRect(Column,0,DummyTC);
    cbfilterBox.top := Column.Grid.Top+1;
    cbfilterBox.left := Column.Grid.left+Arect.Left+1;
    cbFilterbox.Width := Column.Width;
    cbFilterBox.Tag := Integer(Column); //Store the columnPointer
    cbFilterBox.Show;
    cbFilterBox.BringToFront;
    cbFilterBox.DroppedDown := True;
  end;
end;

//Build up the Filter
procedure TForm1.cbFilterBoxChange(Sender: TObject);
begin
  cbFilterBox.Hide;
  if cbFilterBox.Text <> TColumn(cbFilterBox.Tag).Title.Caption then
  begin
    Case TColumn(cbFilterBox.Tag).Field.DataType of
      //Some Fieldtypes
      ftstring :
                 TTable(TDBGrid(TColumn(cbFilterBox.Tag).Grid).Datasource.Dataset).Filter :=
                   TColumn(cbFilterBox.Tag).Field.FieldName+' = '+QuotedStr(cbFilterBox.Text);

      ftInteger,
      ftFloat  :
                 TTable(TDBGrid(TColumn(cbFilterBox.Tag).Grid).Datasource.Dataset).Filter :=
                   TColumn(cbFilterBox.Tag).Field.FieldName+' = '+cbFilterBox.Text;
    end;
    TTable(TDBGrid(TColumn(cbFilterBox.Tag).Grid).Datasource.Dataset).Filtered := True;
  end;
end;

//some Hiding-events
procedure TForm1.cbFilterBoxClick(Sender: TObject);
begin
  cbFilterBox.Hide;
end;

procedure TForm1.cbFilterBoxExit(Sender: TObject);
begin
  cbFilterBox.Hide;
end;

end.

在dbedit keypress上过滤DBGrid上的数据

3 个答案: