DBNull indicates the absence of information, typically in a database application in which a field does not contain any data. The types in the System.Data.SqlTypes namespace have built-in support for DBNull . Note that Value is not the same as the null keyword in C#. The null keyword can be used to release an object by clearing the reference. System.DBNull.Value , on the other hand, is a reference to a special value (a member of the singleton class DBNull ) that is used to indicate missing information. This class has some other uses, namely in COM Interop, in which it represents a VT_EMPTY variant (as opposed to a VT_NULL variant, which is a null reference). public sealed class DBNull : System.Runtime.Serialization.ISerializable, IConvertible { // Public Static Fields public static readonly DBNull Value ; // Public Instance Methods public void GetObjectData (System.Runtime.Serialization.SerializationInfo info , System.Runtime.Serialization.StreamingContext context ) // implements ISerializable public TypeCode GetTypeCode ( ); // implements IConvertible public override string ToString ( ); // overrides object public string ToString (IFormatProvider provider ); // implements IConvertible } |