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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)
public bool Unique { get; set; }

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 void AddColumn(DataTable table)
{
    // Add a DataColumn to the collection and set its properties. 
    // The constructor sets the ColumnName of the column.
    DataColumn column = new DataColumn("Total");
    column.DataType = System.Type.GetType("System.Decimal");
    column.ReadOnly = true;
    column.Expression = "UnitPrice * Quantity";
    column.Unique = false;
}

.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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