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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: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
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