execute ibeblock
as
begin
  stmt = 'select 1 as a from rdb$database';
  for execute statement stmt into :data do
    ibec_ShowMessage(ibec_Coalesce(data['A'], 'NULL'));
end

execute ibeblock
as
begin
  stmt = 'select 1 as a, 2 from rdb$database';
  for execute statement stmt into :data do
    ibec_ShowMessage(ibec_Coalesce(data['A'], 'NULL'));
end