how do rollback operation in som condition

[alisadri1993]

`using(var uow = new UnitOfWork("LosGatos"))
{

            var orangeMackerel = uow.BreedRepository.FindByName("Orange Mackerel");
           **if(orangeMackerel == null)  uow.rollback();**
            var morris = new Cat { BreedId = orangeMackerel.BreedId, Name = "Morris", Age = 12 };
            uow.CatRepository.Add(morris);
            uow.Commit();
        }`

[utsabshrestha]

In catch block the roll back is done if exception ocured.

public void Commit()
{
try
{
_transaction.Commit();
}
catch
{
_transaction.Rollback();
throw;
}
finally
{
_transaction.Dispose();
_transaction = _connection.BeginTransaction();
resetRepositories();
}
}