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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
Definition Examples Remarks Properties Methods Events Extension Methods Applies to Thread Safety 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
Methods
Events
CollectionChanged
Occurs when the columns collection changes, either by adding or removing a column.
Extension Methods
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
©sideway ID: 201100008 Last Updated: 11/8/2020 Revision: 0 Ref:
References
Active Server Pages, , http://msdn.microsoft.com/en-us/library/aa286483.aspx
ASP Overview, , http://msdn.microsoft.com/en-us/library/ms524929%28v=vs.90%29.aspx
ASP Best Practices, , http://technet.microsoft.com/en-us/library/cc939157.aspx
ASP Built-in Objects, , http://msdn.microsoft.com/en-us/library/ie/ms524716(v=vs.90).aspx
Response Object, , http://msdn.microsoft.com/en-us/library/ms525405(v=vs.90).aspx
Request Object, , http://msdn.microsoft.com/en-us/library/ms524948(v=vs.90).aspx
Server Object (IIS), , http://msdn.microsoft.com/en-us/library/ms525541(v=vs.90).aspx
Application Object (IIS), , http://msdn.microsoft.com/en-us/library/ms525360(v=vs.90).aspx
Session Object (IIS), , http://msdn.microsoft.com/en-us/library/ms524319(8v=vs.90).aspx
ASPError Object, , http://msdn.microsoft.com/en-us/library/ms524942(v=vs.90).aspx
ObjectContext Object (IIS), , http://msdn.microsoft.com/en-us/library/ms525667(v=vs.90).aspx
Debugging Global.asa Files, , http://msdn.microsoft.com/en-us/library/aa291249(v=vs.71).aspx
How to: Debug Global.asa files, , http://msdn.microsoft.com/en-us/library/ms241868(v=vs.80).aspx
Calling COM Components from ASP Pages, , http://msdn.microsoft.com/en-us/library/ms524620(v=VS.90).aspx
IIS ASP Scripting Reference, , http://msdn.microsoft.com/en-us/library/ms524664(v=vs.90).aspx
ASP Keywords, , http://msdn.microsoft.com/en-us/library/ms524672(v=vs.90).aspx
Creating Simple ASP Pages, , http://msdn.microsoft.com/en-us/library/ms524741(v=vs.90).aspx
Including Files in ASP Applications, , http://msdn.microsoft.com/en-us/library/ms524876(v=vs.90).aspx
ASP Overview, , http://msdn.microsoft.com/en-us/library/ms524929(v=vs.90).aspx
FileSystemObject Object, , http://msdn.microsoft.com/en-us/library/z9ty6h50(v=vs.84).aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/ms675944(v=vs.85).aspx, , ADO Object Model
ADO Fundamentals, , http://msdn.microsoft.com/en-us/library/windows/desktop/ms680928(v=vs.85).aspx
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