1 <?xml version="1.0" encoding="utf-8"?>
2 <Type Name="DBNull" FullName="System.DBNull">
3 <TypeSignature Maintainer="auto" Language="C#" Value="public sealed class DBNull : IConvertible, System.Runtime.Serialization.ISerializable" />
4 <TypeSignature Language="ILAsm" Value=".class public auto ansi serializable sealed beforefieldinit DBNull extends System.Object implements class System.IConvertible, class System.Runtime.Serialization.ISerializable" />
6 <AssemblyName>mscorlib</AssemblyName>
7 <AssemblyPublicKey>[00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00]</AssemblyPublicKey>
8 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
9 <AssemblyVersion>2.0.0.0</AssemblyVersion>
10 <AssemblyVersion>4.0.0.0</AssemblyVersion>
12 <ThreadSafetyStatement>Gtk# is thread aware, but not thread safe; See the <link location="node:gtk-sharp/programming/threads">Gtk# Thread Programming</link> for details.</ThreadSafetyStatement>
14 <BaseTypeName>System.Object</BaseTypeName>
18 <InterfaceName>System.IConvertible</InterfaceName>
21 <InterfaceName>System.Runtime.Serialization.ISerializable</InterfaceName>
26 <AttributeName>System.Runtime.InteropServices.ComVisible(true)</AttributeName>
31 <attribution license="cc4" from="Microsoft" modified="false" />
32 <para>The <see cref="T:System.DBNull" /> class represents a nonexistent value. In a database, for example, a column in a row of a table might not contain any data whatsoever. That is, the column is considered to not exist at all instead of merely not having a value. A <see cref="T:System.DBNull" /> object represents the nonexistent column. Additionally, COM interop uses the <see cref="T:System.DBNull" /> class to distinguish between a VT_NULL variant, which indicates a nonexistent value, and a VT_EMPTY variant, which indicates an unspecified value.</para>
33 <para>The <see cref="T:System.DBNull" /> type is a singleton class, which means only one <see cref="T:System.DBNull" /> object exists. The <see cref="F:System.DBNull.Value" /> member represents the sole <see cref="T:System.DBNull" /> object. <see cref="F:System.DBNull.Value" /> can be used to explicitly assign a nonexistent value to a database field, although most ADO.NET data providers automatically assign values of <see cref="T:System.DBNull" /> when a field does not have a valid value. You can determine whether a value retrieved from a database field is a <see cref="T:System.DBNull" /> value by passing the value of that field to the DBNull.Value.Equals method. However, some languages and database objects supply methods that make it easier to determine whether the value of a database field is <see cref="F:System.DBNull.Value" />. These include the Visual Basic IsDBNull function, the <see cref="M:System.Convert.IsDBNull(System.Object)" /> method, the <see cref="M:System.Data.DataTableReader.IsDBNull(System.Int32)" /> method, and the <see cref="M:System.Data.IDataRecord.IsDBNull(System.Int32)" /> method.</para>
34 <para>Do not confuse the notion of null in an object-oriented programming language with a <see cref="T:System.DBNull" /> object. In an object-oriented programming language, null means the absence of a reference to an object. <see cref="T:System.DBNull" /> represents an uninitialized variant or nonexistent database column.</para>
37 <attribution license="cc4" from="Microsoft" modified="false" />
38 <para>Represents a nonexistent value. This class cannot be inherited.</para>
42 <Member MemberName="GetObjectData">
43 <MemberSignature Language="C#" Value="public void GetObjectData (System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context);" />
44 <MemberSignature Language="ILAsm" Value=".method public hidebysig newslot virtual instance void GetObjectData(class System.Runtime.Serialization.SerializationInfo info, valuetype System.Runtime.Serialization.StreamingContext context) cil managed" />
45 <MemberType>Method</MemberType>
47 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
48 <AssemblyVersion>2.0.0.0</AssemblyVersion>
49 <AssemblyVersion>4.0.0.0</AssemblyVersion>
52 <ReturnType>System.Void</ReturnType>
55 <Parameter Name="info" Type="System.Runtime.Serialization.SerializationInfo" />
56 <Parameter Name="context" Type="System.Runtime.Serialization.StreamingContext" />
59 <remarks>To be added</remarks>
61 <attribution license="cc4" from="Microsoft" modified="false" />
62 <para>Implements the <see cref="T:System.Runtime.Serialization.ISerializable" /> interface and returns the data needed to serialize the <see cref="T:System.DBNull" /> object.</para>
65 <attribution license="cc4" from="Microsoft" modified="false" />A <see cref="T:System.Runtime.Serialization.SerializationInfo" /> object containing information required to serialize the <see cref="T:System.DBNull" /> object. </param>
66 <param name="context">
67 <attribution license="cc4" from="Microsoft" modified="false" />A <see cref="T:System.Runtime.Serialization.StreamingContext" /> object containing the source and destination of the serialized stream associated with the <see cref="T:System.DBNull" /> object. </param>
70 <Member MemberName="GetTypeCode">
71 <MemberSignature Language="C#" Value="public TypeCode GetTypeCode ();" />
72 <MemberSignature Language="ILAsm" Value=".method public hidebysig newslot virtual instance valuetype System.TypeCode GetTypeCode() cil managed" />
73 <MemberType>Method</MemberType>
75 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
76 <AssemblyVersion>2.0.0.0</AssemblyVersion>
77 <AssemblyVersion>4.0.0.0</AssemblyVersion>
80 <ReturnType>System.TypeCode</ReturnType>
84 <returns>To be added: an object of type 'TypeCode'</returns>
85 <remarks>To be added</remarks>
87 <attribution license="cc4" from="Microsoft" modified="false" />
88 <para>Gets the <see cref="T:System.TypeCode" /> value for <see cref="T:System.DBNull" />.</para>
92 <Member MemberName="System.IConvertible.ToBoolean">
93 <MemberSignature Language="C#" Value="bool IConvertible.ToBoolean (IFormatProvider provider);" />
94 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance bool System.IConvertible.ToBoolean(class System.IFormatProvider provider) cil managed" />
95 <MemberType>Method</MemberType>
97 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
98 <AssemblyVersion>2.0.0.0</AssemblyVersion>
99 <AssemblyVersion>4.0.0.0</AssemblyVersion>
102 <ReturnType>System.Boolean</ReturnType>
105 <Parameter Name="provider" Type="System.IFormatProvider" />
108 <returns>To be added.</returns>
109 <remarks>To be added.</remarks>
111 <attribution license="cc4" from="Microsoft" modified="false" />
112 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
114 <param name="provider">
115 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
118 <Member MemberName="System.IConvertible.ToByte">
119 <MemberSignature Language="C#" Value="byte IConvertible.ToByte (IFormatProvider provider);" />
120 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance unsigned int8 System.IConvertible.ToByte(class System.IFormatProvider provider) cil managed" />
121 <MemberType>Method</MemberType>
123 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
124 <AssemblyVersion>2.0.0.0</AssemblyVersion>
125 <AssemblyVersion>4.0.0.0</AssemblyVersion>
128 <ReturnType>System.Byte</ReturnType>
131 <Parameter Name="provider" Type="System.IFormatProvider" />
134 <returns>To be added.</returns>
135 <remarks>To be added.</remarks>
137 <attribution license="cc4" from="Microsoft" modified="false" />
138 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
140 <param name="provider">
141 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
144 <Member MemberName="System.IConvertible.ToChar">
145 <MemberSignature Language="C#" Value="char IConvertible.ToChar (IFormatProvider provider);" />
146 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance char System.IConvertible.ToChar(class System.IFormatProvider provider) cil managed" />
147 <MemberType>Method</MemberType>
149 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
150 <AssemblyVersion>2.0.0.0</AssemblyVersion>
151 <AssemblyVersion>4.0.0.0</AssemblyVersion>
154 <ReturnType>System.Char</ReturnType>
157 <Parameter Name="provider" Type="System.IFormatProvider" />
160 <returns>To be added.</returns>
161 <remarks>To be added.</remarks>
163 <attribution license="cc4" from="Microsoft" modified="false" />
164 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
166 <param name="provider">
167 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
170 <Member MemberName="System.IConvertible.ToDateTime">
171 <MemberSignature Language="C#" Value="DateTime IConvertible.ToDateTime (IFormatProvider provider);" />
172 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance valuetype System.DateTime System.IConvertible.ToDateTime(class System.IFormatProvider provider) cil managed" />
173 <MemberType>Method</MemberType>
175 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
176 <AssemblyVersion>2.0.0.0</AssemblyVersion>
177 <AssemblyVersion>4.0.0.0</AssemblyVersion>
180 <ReturnType>System.DateTime</ReturnType>
183 <Parameter Name="provider" Type="System.IFormatProvider" />
186 <returns>To be added.</returns>
187 <remarks>To be added.</remarks>
189 <attribution license="cc4" from="Microsoft" modified="false" />
190 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
192 <param name="provider">
193 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
196 <Member MemberName="System.IConvertible.ToDecimal">
197 <MemberSignature Language="C#" Value="decimal IConvertible.ToDecimal (IFormatProvider provider);" />
198 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance valuetype System.Decimal System.IConvertible.ToDecimal(class System.IFormatProvider provider) cil managed" />
199 <MemberType>Method</MemberType>
201 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
202 <AssemblyVersion>2.0.0.0</AssemblyVersion>
203 <AssemblyVersion>4.0.0.0</AssemblyVersion>
206 <ReturnType>System.Decimal</ReturnType>
209 <Parameter Name="provider" Type="System.IFormatProvider" />
212 <returns>To be added.</returns>
213 <remarks>To be added.</remarks>
215 <attribution license="cc4" from="Microsoft" modified="false" />
216 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
218 <param name="provider">
219 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
222 <Member MemberName="System.IConvertible.ToDouble">
223 <MemberSignature Language="C#" Value="double IConvertible.ToDouble (IFormatProvider provider);" />
224 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance float64 System.IConvertible.ToDouble(class System.IFormatProvider provider) cil managed" />
225 <MemberType>Method</MemberType>
227 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
228 <AssemblyVersion>2.0.0.0</AssemblyVersion>
229 <AssemblyVersion>4.0.0.0</AssemblyVersion>
232 <ReturnType>System.Double</ReturnType>
235 <Parameter Name="provider" Type="System.IFormatProvider" />
238 <returns>To be added.</returns>
239 <remarks>To be added.</remarks>
241 <attribution license="cc4" from="Microsoft" modified="false" />
242 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
244 <param name="provider">
245 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
248 <Member MemberName="System.IConvertible.ToInt16">
249 <MemberSignature Language="C#" Value="short IConvertible.ToInt16 (IFormatProvider provider);" />
250 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance int16 System.IConvertible.ToInt16(class System.IFormatProvider provider) cil managed" />
251 <MemberType>Method</MemberType>
253 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
254 <AssemblyVersion>2.0.0.0</AssemblyVersion>
255 <AssemblyVersion>4.0.0.0</AssemblyVersion>
258 <ReturnType>System.Int16</ReturnType>
261 <Parameter Name="provider" Type="System.IFormatProvider" />
264 <returns>To be added.</returns>
265 <remarks>To be added.</remarks>
267 <attribution license="cc4" from="Microsoft" modified="false" />
268 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
270 <param name="provider">
271 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
274 <Member MemberName="System.IConvertible.ToInt32">
275 <MemberSignature Language="C#" Value="int IConvertible.ToInt32 (IFormatProvider provider);" />
276 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance int32 System.IConvertible.ToInt32(class System.IFormatProvider provider) cil managed" />
277 <MemberType>Method</MemberType>
279 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
280 <AssemblyVersion>2.0.0.0</AssemblyVersion>
281 <AssemblyVersion>4.0.0.0</AssemblyVersion>
284 <ReturnType>System.Int32</ReturnType>
287 <Parameter Name="provider" Type="System.IFormatProvider" />
290 <returns>To be added.</returns>
291 <remarks>To be added.</remarks>
293 <attribution license="cc4" from="Microsoft" modified="false" />
294 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
296 <param name="provider">
297 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
300 <Member MemberName="System.IConvertible.ToInt64">
301 <MemberSignature Language="C#" Value="long IConvertible.ToInt64 (IFormatProvider provider);" />
302 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance int64 System.IConvertible.ToInt64(class System.IFormatProvider provider) cil managed" />
303 <MemberType>Method</MemberType>
305 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
306 <AssemblyVersion>2.0.0.0</AssemblyVersion>
307 <AssemblyVersion>4.0.0.0</AssemblyVersion>
310 <ReturnType>System.Int64</ReturnType>
313 <Parameter Name="provider" Type="System.IFormatProvider" />
316 <returns>To be added.</returns>
317 <remarks>To be added.</remarks>
319 <attribution license="cc4" from="Microsoft" modified="false" />
320 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
322 <param name="provider">
323 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
326 <Member MemberName="System.IConvertible.ToSByte">
327 <MemberSignature Language="C#" Value="sbyte IConvertible.ToSByte (IFormatProvider provider);" />
328 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance int8 System.IConvertible.ToSByte(class System.IFormatProvider provider) cil managed" />
329 <MemberType>Method</MemberType>
331 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
332 <AssemblyVersion>2.0.0.0</AssemblyVersion>
333 <AssemblyVersion>4.0.0.0</AssemblyVersion>
336 <ReturnType>System.SByte</ReturnType>
339 <Parameter Name="provider" Type="System.IFormatProvider" />
342 <returns>To be added.</returns>
343 <remarks>To be added.</remarks>
345 <attribution license="cc4" from="Microsoft" modified="false" />
346 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
348 <param name="provider">
349 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
352 <Member MemberName="System.IConvertible.ToSingle">
353 <MemberSignature Language="C#" Value="float IConvertible.ToSingle (IFormatProvider provider);" />
354 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance float32 System.IConvertible.ToSingle(class System.IFormatProvider provider) cil managed" />
355 <MemberType>Method</MemberType>
357 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
358 <AssemblyVersion>2.0.0.0</AssemblyVersion>
359 <AssemblyVersion>4.0.0.0</AssemblyVersion>
362 <ReturnType>System.Single</ReturnType>
365 <Parameter Name="provider" Type="System.IFormatProvider" />
368 <returns>To be added.</returns>
369 <remarks>To be added.</remarks>
371 <attribution license="cc4" from="Microsoft" modified="false" />
372 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
374 <param name="provider">
375 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
378 <Member MemberName="System.IConvertible.ToType">
379 <MemberSignature Language="C#" Value="object IConvertible.ToType (Type targetType, IFormatProvider provider);" />
380 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance object System.IConvertible.ToType(class System.Type targetType, class System.IFormatProvider provider) cil managed" />
381 <MemberType>Method</MemberType>
383 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
384 <AssemblyVersion>2.0.0.0</AssemblyVersion>
385 <AssemblyVersion>4.0.0.0</AssemblyVersion>
388 <ReturnType>System.Object</ReturnType>
391 <Parameter Name="targetType" Type="System.Type" />
392 <Parameter Name="provider" Type="System.IFormatProvider" />
395 <param name="targetType">To be added.</param>
396 <returns>To be added.</returns>
398 <attribution license="cc4" from="Microsoft" modified="false" />
399 <para>Three conversions are supported: If the <paramref name="type" /> parameter specifies <see cref="T:System.Object" /> or <see cref="T:System.DBNull" />, the return value is the current <see cref="T:System.DBNull" /> object itself. If the <paramref name="type" /> parameter specifies <see cref="T:System.String" />, the return value is the string returned by the <see cref="M:System.DBNull.ToString" /> method.</para>
402 <attribution license="cc4" from="Microsoft" modified="false" />
403 <para>Converts the current <see cref="T:System.DBNull" /> object to the specified type.</para>
405 <param name="provider">
406 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface and is used to augment the conversion. If null is specified, format information is obtained from the current culture. </param>
409 <Member MemberName="System.IConvertible.ToUInt16">
410 <MemberSignature Language="C#" Value="ushort IConvertible.ToUInt16 (IFormatProvider provider);" />
411 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance unsigned int16 System.IConvertible.ToUInt16(class System.IFormatProvider provider) cil managed" />
412 <MemberType>Method</MemberType>
414 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
415 <AssemblyVersion>2.0.0.0</AssemblyVersion>
416 <AssemblyVersion>4.0.0.0</AssemblyVersion>
419 <ReturnType>System.UInt16</ReturnType>
422 <Parameter Name="provider" Type="System.IFormatProvider" />
425 <returns>To be added.</returns>
426 <remarks>To be added.</remarks>
428 <attribution license="cc4" from="Microsoft" modified="false" />
429 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
431 <param name="provider">
432 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
435 <Member MemberName="System.IConvertible.ToUInt32">
436 <MemberSignature Language="C#" Value="uint IConvertible.ToUInt32 (IFormatProvider provider);" />
437 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance unsigned int32 System.IConvertible.ToUInt32(class System.IFormatProvider provider) cil managed" />
438 <MemberType>Method</MemberType>
440 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
441 <AssemblyVersion>2.0.0.0</AssemblyVersion>
442 <AssemblyVersion>4.0.0.0</AssemblyVersion>
445 <ReturnType>System.UInt32</ReturnType>
448 <Parameter Name="provider" Type="System.IFormatProvider" />
451 <returns>To be added.</returns>
452 <remarks>To be added.</remarks>
454 <attribution license="cc4" from="Microsoft" modified="false" />
455 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
457 <param name="provider">
458 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
461 <Member MemberName="System.IConvertible.ToUInt64">
462 <MemberSignature Language="C#" Value="ulong IConvertible.ToUInt64 (IFormatProvider provider);" />
463 <MemberSignature Language="ILAsm" Value=".method hidebysig newslot virtual instance unsigned int64 System.IConvertible.ToUInt64(class System.IFormatProvider provider) cil managed" />
464 <MemberType>Method</MemberType>
466 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
467 <AssemblyVersion>2.0.0.0</AssemblyVersion>
468 <AssemblyVersion>4.0.0.0</AssemblyVersion>
471 <ReturnType>System.UInt64</ReturnType>
474 <Parameter Name="provider" Type="System.IFormatProvider" />
477 <returns>To be added.</returns>
478 <remarks>To be added.</remarks>
480 <attribution license="cc4" from="Microsoft" modified="false" />
481 <para>This conversion is not supported. Attempting to make this conversion throws an <see cref="T:System.InvalidCastException" />.</para>
483 <param name="provider">
484 <attribution license="cc4" from="Microsoft" modified="false" />An object that implements the <see cref="T:System.IFormatProvider" /> interface. (This parameter is not used; specify null.)</param>
487 <Member MemberName="ToString">
488 <MemberSignature Language="C#" Value="public override string ToString ();" />
489 <MemberSignature Language="ILAsm" Value=".method public hidebysig virtual instance string ToString() cil managed" />
490 <MemberType>Method</MemberType>
492 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
493 <AssemblyVersion>2.0.0.0</AssemblyVersion>
494 <AssemblyVersion>4.0.0.0</AssemblyVersion>
497 <ReturnType>System.String</ReturnType>
501 <returns>To be added.</returns>
502 <remarks>To be added.</remarks>
504 <attribution license="cc4" from="Microsoft" modified="false" />
505 <para>Returns an empty string (<see cref="F:System.String.Empty" />).</para>
509 <Member MemberName="ToString">
510 <MemberSignature Language="C#" Value="public string ToString (IFormatProvider provider);" />
511 <MemberSignature Language="ILAsm" Value=".method public hidebysig newslot virtual instance string ToString(class System.IFormatProvider provider) cil managed" />
512 <MemberType>Method</MemberType>
514 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
515 <AssemblyVersion>2.0.0.0</AssemblyVersion>
516 <AssemblyVersion>4.0.0.0</AssemblyVersion>
519 <ReturnType>System.String</ReturnType>
522 <Parameter Name="provider" Type="System.IFormatProvider" />
525 <returns>To be added: an object of type 'string'</returns>
526 <remarks>To be added</remarks>
528 <attribution license="cc4" from="Microsoft" modified="false" />
529 <para>Returns an empty string using the specified <see cref="T:System.IFormatProvider" />.</para>
531 <param name="provider">
532 <attribution license="cc4" from="Microsoft" modified="false" />The <see cref="T:System.IFormatProvider" /> to be used to format the return value.</param>
535 <Member MemberName="Value">
536 <MemberSignature Language="C#" Value="public static readonly DBNull Value;" />
537 <MemberSignature Language="ILAsm" Value=".field public static initonly class System.DBNull Value" />
538 <MemberType>Field</MemberType>
540 <AssemblyVersion>1.0.5000.0</AssemblyVersion>
541 <AssemblyVersion>2.0.0.0</AssemblyVersion>
542 <AssemblyVersion>4.0.0.0</AssemblyVersion>
545 <ReturnType>System.DBNull</ReturnType>
550 <attribution license="cc4" from="Microsoft" modified="false" />
552 <see cref="T:System.DBNull" /> is a singleton class, which means only this instance of this class can exist.</para>
553 <para>If a database field has missing data, you can use the <see cref="F:System.DBNull.Value" /> property to explicitly assign a <see cref="T:System.DBNull" /> object value to the field. However, most data providers do this automatically.</para>
554 <para>To evaluate database fields to determine whether their values are <see cref="T:System.DBNull" />, you can pass the field value to the DBNull.Value.Equals method. However, this method is rarely used because there are a number of other ways to evaluate a database field for missing data. These include the Visual Basic IsDBNull function, the <see cref="M:System.Convert.IsDBNull(System.Object)" /> method, the <see cref="M:System.Data.DataTableReader.IsDBNull(System.Int32)" /> method, the <see cref="M:System.Data.IDataRecord.IsDBNull(System.Int32)" /> method, and several other methods.</para>
557 <attribution license="cc4" from="Microsoft" modified="false" />
558 <para>Represents the sole instance of the <see cref="T:System.DBNull" /> class.</para>