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System.Data Namespace Component
DataColumnCollection Class
 Definition
  In this article
 Examples
 Remarks
 Properties
 Methods
 Events
 Extension Methods
 Applies to
   .NET Core
   .NET Framework
   .NET Standard
   Xamarin.Android
   Xamarin.iOS
   Xamarin.Mac
 Thread Safety
 See also
 Examples
 Source/Reference

System.Data Namespace Component

The System.Data namespace provides access to classes that represent the ADO.NET architecture. ADO.NET lets you build components that efficiently manage data from multiple data sources.

DataColumnCollection Class

Definition

Namespace:
System.Data
Assemblies:
System.Data.dll, netstandard.dll, System.Data.Common.dll

Represents a collection of DataColumn objects for a DataTable.

In this article

  1. Definition
  2. Examples
  3. Remarks
  4. Properties
  5. Methods
  6. Events
  7. Extension Methods
  8. Applies to
  9. Thread Safety
  10. See also
C#
[System.Serializable]
public sealed class DataColumnCollection : System.Data.InternalDataCollectionBase
Inheritance
Object InternalDataCollectionBase DataColumnCollection
Attributes
SerializableAttribute

Examples

The following example iterates through a collection of DataColumn objects and prints various properties of each column in the collection.

C#
private void PrintDataTableColumnInfo(DataTable table)
{
    // Use a DataTable object's DataColumnCollection.
    DataColumnCollection columns = table.Columns;

    // Print the ColumnName and DataType for each column.
    foreach(DataColumn column in columns)
    {
        Console.WriteLine(column.ColumnName);
        Console.WriteLine(column.DataType);
    }
}

Remarks

The DataColumnCollection defines the schema of a DataTable, and determines what kind of data each DataColumn can contain. You can access the DataColumnCollection through the Columns property of the DataTable object.

The DataColumnCollection uses the Add and Remove methods to insert and delete DataColumn objects. Use the Count property to determine how many DataColumn objects are in the collection. Use the Contains method to verify whether a specified index or column name exists in the collection.

Properties

Count

Gets the total number of elements in a collection.

(Inherited from InternalDataCollectionBase)
IsReadOnly

Gets a value that indicates whether the InternalDataCollectionBase is read-only.

(Inherited from InternalDataCollectionBase)
IsSynchronized

Gets a value that indicates whether the InternalDataCollectionBase is synchronized.

(Inherited from InternalDataCollectionBase)
Item[Int32]

Gets the DataColumn from the collection at the specified index.

Item[String]

Gets the DataColumn from the collection with the specified name.

List

Gets the items of the collection as a list.

(Inherited from InternalDataCollectionBase)
SyncRoot

Gets an object that can be used to synchronize the collection.

(Inherited from InternalDataCollectionBase)

Methods

Add()

Creates and adds a DataColumn object to the DataColumnCollection.

Add(DataColumn)

Creates and adds the specified DataColumn object to the DataColumnCollection.

Add(String)

Creates and adds a DataColumn object that has the specified name to the DataColumnCollection.

Add(String, Type)

Creates and adds a DataColumn object that has the specified name and type to the DataColumnCollection.

Add(String, Type, String)

Creates and adds a DataColumn object that has the specified name, type, and expression to the DataColumnCollection.

AddRange(DataColumn[])

Copies the elements of the specified DataColumn array to the end of the collection.

CanRemove(DataColumn)

Checks whether a specific column can be removed from the collection.

Clear()

Clears the collection of any columns.

Contains(String)

Checks whether the collection contains a column with the specified name.

CopyTo(Array, Int32)

Copies all the elements of the current InternalDataCollectionBase to a one-dimensional Array, starting at the specified InternalDataCollectionBase index.

(Inherited from InternalDataCollectionBase)
CopyTo(DataColumn[], Int32)

Copies the entire collection into an existing array, starting at a specified index within the array.

Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetEnumerator()

Gets an IEnumerator for the collection.

(Inherited from InternalDataCollectionBase)
GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetType()

Gets the Type of the current instance.

(Inherited from Object)
IndexOf(DataColumn)

Gets the index of a column specified by name.

IndexOf(String)

Gets the index of the column with the specific name (the name is not case sensitive).

MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
Remove(DataColumn)

Removes the specified DataColumn object from the collection.

Remove(String)

Removes the DataColumn object that has the specified name from the collection.

RemoveAt(Int32)

Removes the column at the specified index from the collection.

ToString()

Returns a string that represents the current object.

(Inherited from Object)

Events

CollectionChanged

Occurs when the columns collection changes, either by adding or removing a column.

Extension Methods

Cast<TResult>(IEnumerable)

Casts the elements of an IEnumerable to the specified type.

OfType<TResult>(IEnumerable)

Filters the elements of an IEnumerable based on a specified type.

AsParallel(IEnumerable)

Enables parallelization of a query.

AsQueryable(IEnumerable)

Converts an IEnumerable to an IQueryable.

Applies to

.NET Core

3.0 Preview 8 2.2 2.1 2.0

.NET Framework

4.8 4.7.2 4.7.1 4.7 4.6.2 4.6.1 4.6 4.5.2 4.5.1 4.5 4.0 3.5 3.0 2.0 1.1

.NET Standard

2.1 Preview 2.0

Xamarin.Android

7.1

Xamarin.iOS

10.8

Xamarin.Mac

3.0

Thread Safety

This type is safe for multithreaded read operations. You must synchronize any write operations.

See also

 

Examples

Examples of DataColumnCollection Class
ASP.NET Code Input:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
       <title>Sample Page</title>
       <meta http-equiv="Content-Type" content="text/html;charset=utf-8">
       <script runat="server" >
           Sub Page_Load()
               Dim xstr As String
               Dim xconn As New System.Data.OleDb.OleDbConnection
               xconn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=T:\test.mdb;User Id=admin;Password=;"
               xconn.Open()
               xstr = xstr + "Connection xconn to database test.mdb  is opened successfully.<br />"
               Dim xdata As New System.Data.DataSet
               Dim xadapt As System.Data.OleDb.OleDbDataAdapter
               Dim sql As String = "SELECT * FROM T1"
               xadapt = New System.Data.OleDb.OleDbDataAdapter(sql, xconn)
               xstr = xstr + "Dataadapter xadapt is assigned to SELECT * FROM T1 through xconn successfully.<br />"
               xadapt.Fill(xdata,"T1")
               xstr = xstr + "Dataset xdata is filled by xadapt.fill successfully.<br />"
               xstr = xstr + "<br />"
               Dim xcols As System.Data.DataColumnCollection
               xstr = xstr + "Declare a table column collection, xcols<br />"
               xcols = xdata.tables(0).Columns
               xstr = xstr + "Assign xdata.tables(0).Columns to table columncollection, xcols <br />"
               xstr = xstr  + "->xcols.Count: " + xcols.Count.ToString + "<br />"
               xstr = xstr  + "->xcols.Item(0).ColumnName: " + xcols.Item(0).ColumnName + "<br />"
               xstr = xstr  + "->xcols.Item(id).DataType: " + xcols.Item("id").DataType.ToString + "<br />"
               xstr = xstr  + "xcols.IndexOf(id): " + xcols.IndexOf("id").ToString + "<br />"
               xstr = xstr  + "xcols.Add(extra1): " + xcols.Add("extra1").ToString + "<br />"
               xstr = xstr  + "xcols.Add(extra2): " + xcols.Add("extra2").ToString + "<br />"
               xstr = xstr  + "xcols.IndexOf(extra1): " + xcols.IndexOf("extra1").ToString + "<br />"
               xstr = xstr  + "->xcols.Count: " + xcols.Count.ToString + "<br />"
               xcols.RemoveAt(4)
               xstr = xstr  + "column extra2 is removed by xcols.RemoveAt(4)<br />"
               xcols.Remove("extra1")
               xstr = xstr  + "column extra1 is removed by xcols.Remove(extra1)<br />"
               xstr = xstr  + "->xcols.Count: " + xcols.Count.ToString + "<br />"
               xcols.Clear()
               xstr = xstr  + "columncollection xcols is cleared by xcols.Clear()<br />"
               xstr = xstr  + "->xcols.Count: " + xcols.Count.ToString + "<br />"
               
               xstr = xstr + "<br />"
               xadapt.Dispose()
               xstr = xstr + "Dataadapter xadapt is disposed successfully.<br />"
               xconn.Close()
               xstr = xstr + "Connection xconn is closed successfully.<br />"
               xdata.Dispose()
               xstr = xstr + "Dataset xdata is disposed successfully.<br />"
               
               lbl01.Text = xstr
           End Sub
       </script>
    </head>
    <body>
       <% Response.Write ("<h1>This is a Sample Page of DataColumnCollection Class</h1>") %>
       <p>
           <%-- Set on Page_Load --%>
           <asp:Label id="lbl01" runat="server" />
       </p>
    </body>
</html>
HTML Web Page Embedded Output:

Source/Reference


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ID: 201100008 Last Updated: 8/11/2020 Revision: 0 Ref:

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References

  1. Active Server Pages,  , http://msdn.microsoft.com/en-us/library/aa286483.aspx
  2. ASP Overview,  , http://msdn.microsoft.com/en-us/library/ms524929%28v=vs.90%29.aspx
  3. ASP Best Practices,  , http://technet.microsoft.com/en-us/library/cc939157.aspx
  4. ASP Built-in Objects,  , http://msdn.microsoft.com/en-us/library/ie/ms524716(v=vs.90).aspx
  5. Response Object,  , http://msdn.microsoft.com/en-us/library/ms525405(v=vs.90).aspx
  6. Request Object,  , http://msdn.microsoft.com/en-us/library/ms524948(v=vs.90).aspx
  7. Server Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms525541(v=vs.90).aspx
  8. Application Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms525360(v=vs.90).aspx
  9. Session Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms524319(8v=vs.90).aspx
  10. ASPError Object,  , http://msdn.microsoft.com/en-us/library/ms524942(v=vs.90).aspx
  11. ObjectContext Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms525667(v=vs.90).aspx
  12. Debugging Global.asa Files,  , http://msdn.microsoft.com/en-us/library/aa291249(v=vs.71).aspx
  13. How to: Debug Global.asa files,  , http://msdn.microsoft.com/en-us/library/ms241868(v=vs.80).aspx
  14. Calling COM Components from ASP Pages,  , http://msdn.microsoft.com/en-us/library/ms524620(v=VS.90).aspx
  15. IIS ASP Scripting Reference,  , http://msdn.microsoft.com/en-us/library/ms524664(v=vs.90).aspx
  16. ASP Keywords,  , http://msdn.microsoft.com/en-us/library/ms524672(v=vs.90).aspx
  17. Creating Simple ASP Pages,  , http://msdn.microsoft.com/en-us/library/ms524741(v=vs.90).aspx
  18. Including Files in ASP Applications,  , http://msdn.microsoft.com/en-us/library/ms524876(v=vs.90).aspx
  19. ASP Overview,  , http://msdn.microsoft.com/en-us/library/ms524929(v=vs.90).aspx
  20. FileSystemObject Object,  , http://msdn.microsoft.com/en-us/library/z9ty6h50(v=vs.84).aspx
  21. http://msdn.microsoft.com/en-us/library/windows/desktop/ms675944(v=vs.85).aspx,  , ADO Object Model
  22. ADO Fundamentals,  , http://msdn.microsoft.com/en-us/library/windows/desktop/ms680928(v=vs.85).aspx
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