ConstraintCollection.Add Method (String, DataColumn[], Boolean)


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Constructs a new UniqueConstraint with the specified name, array of DataColumn objects, and value that indicates whether the column is a primary key, and adds it to the collection.

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

public Constraint Add(
	string name,
	DataColumn[] columns,
	bool primaryKey


Type: System.String

The name of the UniqueConstraint.

Type: System.Data.DataColumn[]

An array of DataColumn objects to which the constraint applies.

Type: System.Boolean

Specifies whether the column should be the primary key. If true, the column will be a primary key column.

Return Value

Type: System.Data.Constraint

A new UniqueConstraint.

Exception Condition

The constraint already belongs to this collection.


The constraint belongs to another collection.


The collection already has a constraint with the specified name. (The comparison is not case-sensitive.)

The CollectionChanged event occurs if the constraint is added successfully.

The following example creates an array of DataColumn objects that are used to create a new UniqueConstraint in a specific DataTable.

private void AddUniqueConstraint(DataTable table)
    DataColumn[] columns = new DataColumn[1];
    columns[0] = table.Columns["ID"];
    columns[1] = table.Columns["Name"];
    table.Constraints.Add("idNameConstraint", columns, true);

.NET Framework
Available since 1.1
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