You ignore specific elements with specification public MyClass { public int? a { get; set; } [System.Xml.Serialization.XmlIgnore] public bool aSpecified { get { return this.a != null; } } public int? b { get; set; } [System.Xml.Serialization.XmlIgnore] public bool bSpecified { get { return this.b != null; } } public int? c { get; set; … Read more
long is the same as Int64 long data type The ? means it is nullable A nullable type can represent the normal range of values for its underlying value type, plus an additional null value Nullable Types Nullable example: int? num = null; if (num.HasValue == true) { System.Console.WriteLine(“num = ” + num.Value); } else … Read more
public static T To<T>(this IConvertible obj) { Type t = typeof(T); Type u = Nullable.GetUnderlyingType(t); if (u != null) { return (obj == null) ? default(T) : (T)Convert.ChangeType(obj, u); } else { return (T)Convert.ChangeType(obj, t); } }
You need to use .Value first (Since it’s nullable). var shortString = yourDate.Value.ToShortDateString(); But also check that yourDate has a value: if (yourDate.HasValue) { var shortString = yourDate.Value.ToShortDateString(); }
You can do the IsNull or NVL stuff, but it’s just going to make the engine do more work. You’ll be calling functions to do column conversions which then have to have the results compared. Use what you have where ((MYCOLUMN=SEARCHVALUE) OR (MYCOLUMN is NULL and SEARCHVALUE is NULL))
If you look at the IL using Ildasm, you’ll find that they both compile down to Nullable<bool>.
You can take a look at how compiler lowers this code: int? a = 3; Sample<int> sampleA = a; into this: int? nullable = 3; int? nullable2 = nullable; Sample<int> sample = nullable2.HasValue ? ((Sample<int>)nullable2.GetValueOrDefault()) : null; Because Sample<int> is a class its instance can be assigned a null value and with such an implicit … Read more
What to do if you are using C# 9 In C# 9, you can use T? on an unconstrained type parameter to indicate that the type is always nullable when T is a reference type. In fact, the example in the original question “just works” after adding ? to the property and constructor parameter. See … Read more
You can always switch to fill.travel.GetValueOrDefault() To provide the default (false), or the value of the boolean column from the database. Or you can specify the default with an overload. Either way, the nullable currently doesnt have a value, which is why you get that exception.
Laramie is right about the bitmap and links to the right place in the manual. Yet, this is almost, but not quite correct: So for any given row with one or more nulls, the size added to it would be that of the bitmap(N bits for an N-column table, rounded up). One has to factor … Read more