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 bool Unique { get; set; }

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 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
Available since 1.1
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