Add Method (String, Type)

DataColumnCollection.Add Method (String, Type)

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

Namespace: System.Data
Assembly: System.Data (in

public DataColumn Add (
	string columnName,
	Type type
public DataColumn Add (
	String columnName, 
	Type type
public function Add (
	columnName : String, 
	type : Type
) : DataColumn



The ColumnName to use when you create the column.


The DataType of the new column.

Return Value

The newly created DataColumn.

Exception typeCondition


The collection already has a column with the specified name. (The comparison is not case-sensitive.)


The expression is invalid. See the Expression property for more information about how to create expressions.

If a null reference (Nothing in Visual Basic) or an empty string ("") is passed in for the name, a default name ("Column1", "Column2", and so on) is given to the column.

Use the Contains method to determine whether a column with the proposed name already exists in the collection.

If the collection is successfully changed by adding or removing columns, the CollectionChanged event occurs.

The following example creates and adds a new DataColumn to a DataColumnCollection of a DataTable.

Private Sub AddColumn()
    Dim columns As DataColumnCollection = _
    ' Add a new column and return it.
    Dim column As DataColumn = columns.Add( _
        "Total", System.Type.GetType("System.Decimal"))
    column.ReadOnly = True
    column.Unique = False
End Sub

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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