procedure TForm2.Button1Click(Sender: TObject);

begin

  if not FDConnection1.Connected then

    FDConnection1.Connected := True;

//  FDQuery1.SQL.Text := 'select getdate()';

  FDQuery1.Open('select getdate()');

  Caption := FDQuery1.Fields[0].AsString;

  //FDQuery1.Close;

  FDConnection1.Connected := False;

end;

procedure TForm2.FormCreate(Sender: TObject);

var

  Def: IFDStanConnectionDef;

begin

  Def := FDManager1.ConnectionDefs.FindConnectionDef('PoolTest');

  if Def=nil then

    Def := FDManager1.ConnectionDefs.AddConnectionDef;

  Def.Name := 'PoolTest';

  Def.Params.DriverID := 'mssql';

  Def.Params.Values['Server'] := 'JJW-PC';

  Def.Params.Database := 'TJZFDB';

  Def.Params.UserName := 'sa';

  Def.Params.Password := 'Sa12345';

  Def.Params.Pooled := True;

  Def.MarkPersistent;

  Def.Apply;

  FDConnection1.ConnectionDefName := 'PoolTest';

end;

经测试，动态添加连接池在第一次里有延迟，第二次就很多了，事件探查器中发现，多次点击button,最多只有2个连接。