function TDataMD_Base.GetFreeQuery: TADOQuery;
var
  mq: TADOQuery;
  i: Integer;
begin
  while FLockQueryList do
    Application.ProcessMessages;

  FLockQueryList := True;
  Result := nil;
  if not Assigned(FQueryList) then
    FQueryList := TStringList.Create
  else
  begin
    for i := 0 to FQueryList.Count - 1 do
    begin
      mq := TADOQuery(FQueryList.Objects[i]);
      if not mq.Active then
      begin
        Result := mq;
        Break;
      end;
    end;
  end;
  if not Assigned(Result) then
  begin
    mq := TADOQuery.Create(self);
    mq.Connection := ADOConn_Base;
    FQueryList.AddObject(inttostr(FQueryList.Count), mq);
    Result := mq;
  end;
  FLockQueryList := False;
end;

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
    FLock:Boolean;
    k:Integer;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
begin
  inherited;
  FLock:=True;
  k:=0;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  while FLock do
    Application.ProcessMessages;
  Self.Caption:=Self.Caption+inttostr(k)+'+';
  Inc(k); 
  FLock :=True;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  FLock:=False
end;

end.