要比较两个 Nullable<T> 对象，请使用 Nullable.Compare<T> 喜欢:

To compare two Nullable<T> objects use Nullable.Compare<T> like:

bool result = Nullable.Compare(birthDate, hireDate) > 0;

你也可以这样做:

You can also do:

使用 Nullable DateTime 的 Value 属性.(记得检查两个对象是否都有一些值)

Use the Value property of the Nullable DateTime. (Remember to check if both object Has some values)

if ((birthDate.HasValue && hireDate.HasValue) 
    && DateTime.Compare(birthDate.Value, hireDate.Value) > 0)
{
}

如果两个值都相同 DateTime.Compare 将返回您 0

If both values are Same DateTime.Compare will return you 0

类似的东西

DateTime? birthDate = new DateTime(2000, 1, 1);
DateTime? hireDate = new DateTime(2013, 1, 1);
if ((birthDate.HasValue && hireDate.HasValue) 
    && DateTime.Compare(birthDate.Value, hireDate.Value) > 0)
{
}