delphi数据库查询

procedure TForm1.Button1Click(Sender: TObject);
begin
  Query1.SQL.Clear;
  Query1.SQL.Add('SELECT * FROM Customers WHERE City = :City');
  Query1.Params.ParamByName('City').Value := 'Berlin';
  Query1.Open;
  if Query1.IsEmpty then
    ShowMessage('没有找到符合条件的记录')
  else
    ShowMessage('查询成功');
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Database1.Params.Add('DatabaseName=YourDatabase');
  Database1.Params.Add('User_Name=YourUsername');
  Database1.Params.Add('Password=YourPassword');
  try
    Database1.Connected := True;
  except
    on E: Exception do
      ShowMessage('数据库连接失败: ' + E.Message);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Query1.SQL.Clear;
  Query1.SQL.Add('SELECT * FROM Customers WHERE CustomerID = :CustomerID');
  Query1.Params.ParamByName('CustomerID').Value := Edit1.Text;
  Query1.Open;
end;