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DataColumn Constructor (String, Type, String)

Initializes a new instance of the DataColumn class using the specified name, data type, and expression.

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

'Declaration
Public Sub New ( _
	columnName As String, _
	dataType As Type, _
	expr As String _
)
'Usage
Dim columnName As String 
Dim dataType As Type 
Dim expr As String 

Dim instance As New DataColumn(columnName, _
	dataType, expr)

Parameters

columnName
Type: System.String

A string that represents the name of the column to be created. If set to Nothing or an empty string (""), a default name will be specified when added to the columns collection.

dataType
Type: System.Type

A supported DataType.

expr
Type: System.String

The expression used to create this column. For more information, see the Expression property.

ExceptionCondition
ArgumentNullException

No dataType was specified.

The following example creates a computed column.

Private Sub AddDataColumn(ByVal table As DataTable)
    Dim column As DataColumn 
    Dim decimalType As System.Type

    decimalType = System.Type.GetType("System.Decimal")
    column = New DataColumn("Tax", decimalType, "UnitPrice * .0862")

    ' Set various properties. 
    With column
       .AutoIncrement = False
       .ReadOnly = True 
    End With 

    ' Add to Columns collection.
    table.Columns.Add(column)
 End Sub

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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