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DataColumn.Unique Property

Gets or sets a value that indicates whether the values in each row of the column must be unique.

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

'Declaration
Public Property Unique As Boolean

Property Value

Type: System.Boolean
true if the value must be unique; otherwise, false. The default is false.

ExceptionCondition
ArgumentException

The column is a calculated column.

As soon as this property is changed from false to true, a unique constraint will be created on this column to make sure that values are unique.

The following example creates new DataColumn, sets its properties, and adds it to a table's columns collection.


Private Sub AddColumn(table As DataTable)
    ' Add a DataColumn to the collection and set its properties.
    ' The constructor sets the ColumnName of the column.
    Dim column As DataColumn = New DataColumn("Total")
    column.DataType = System.Type.GetType("System.Decimal")
    column.ReadOnly = True
    column.Expression = "UnitPrice * Quantity"
    column.Unique = False
End Sub


.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

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.

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