Obtenir le nom de l'utilisateur connecté à une base de données

function TDM.GetLoggedUserName: string;
var
IBQuery: TIBQuery;
begin
result := '';

IBQuery := TIBQuery.Create(nil);
try
with IBQuery do begin
Database := IBDB;
Transaction := TibTransaction.Create(nil);
Transaction.DefaultDatabase := IBDB;
try
Transaction.StartTransaction;
SQL.Add('SELECT USER FROM rdb$database');

Prepare;
Open;
try
if FindField('USER') = nil then exit;

result := FieldByName('USER').AsString;

Transaction.Commit;
finally
Close;
end;
finally
Transaction.Active := False;
Transaction.Free;
end;
end; //with IBQuery
finally
IBQuery.Free;
end;
end;

procedure TfMain.Button2Click(Sender: TObject);
begin
Showmessage('utilisateur '+ DM.GetLoggedUserName);
end;