Unique Property

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)

Public Property Unique As Boolean

Property Value

Type: System.Boolean

true if the value must be unique; otherwise, false. The default is false.

Exception Condition

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
Available since 1.1
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