procedure TForm1.Button1Click(Sender: TObject);
begin
Query1.sql.text:= 'Select Clave,nombre,domicilio from Usuarios where Clave =:Cla';
Query1.Parameters[0].Value:= Edit1.Text;
Query1.Open;
If Query1.FilebyName('Clave').AsString = Edit1.Text then
Begin
Edit2.text:= Query1.filebyname('nombre').AsString;
Edit3.text:= Query1.filebyname('domicilio').AsString;
end
else
MessageDlg('Clave Inválida',mtError, [mbOK], 0);
Edit1.Text := '';
Edit1.SetFocus;
Query1.Active := False;
end;