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DataColumnCollection.Add Method (String, Type, String)

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

Namespace:  System.Data
Assembly:  System.Data (in System.Data.dll)
member Add : 
        columnName:string * 
        type:Type * 
        expression:string -> DataColumn

Parameters

columnName
Type: System.String

The name to use when you create the column.

type
Type: System.Type

The DataType of the new column.

expression
Type: System.String

The expression to assign to the Expression property.

Return Value

Type: System.Data.DataColumn
The newly created DataColumn.
ExceptionCondition
DuplicateNameException

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

InvalidExpressionException

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()
    ' Get the DataColumnCollection of a table in a DataSet. 
    Dim columns As DataColumnCollection = _
        DataSet1.Tables("Orders").Columns

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

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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