Name
DBNull
Synopsis
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 field DBNull Value; // Public Instance Methods public method void GetObjectData( // implements ISerializable System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context); public method TypeCode GetTypeCode(); // implements IConvertible public override method string ToString(); // overrides object public method string ToString(IFormatProvider provider); // implements IConvertible }
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