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DataColumnCollection.Add Method (String, Type, String)

.NET Framework 4

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)

public DataColumn Add(
	string columnName,
	Type type,
	string expression
)

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.

Exceptions

Exception	Condition
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.

Remarks

If null 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.

Examples

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

Version Information

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Reference

DataColumnCollection Class

Add Overload

System.Data Namespace

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