NGWS SDK Documentation  

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UniqueConstraint Class

Represents a restriction on a set of columns in which all values must be unique.

Object
   Constraint
      UniqueConstraint

[Visual Basic]
Public Class UniqueConstraint
   Inherits Constraint
[C#]
public class UniqueConstraint : Constraint
[C++]
public __gc class UniqueConstraint : public Constraint
[JScript]
public class UniqueConstraint extends Constraint

Remarks

The UniqueConstraint is enforced on a single column (or columns) to ensure that a primary key value is unique.

Constraints are not enforced unless the EnforceConstraints property is set to true.

When the a DataSet is merged with a second DataSet, constraints are not enforced until all merges are completed.

Requirements

Namespace: System.Data

Assembly: System.Data.dll

Example [Visual Basic]

The following example adds a UniqueConstraint to a DataSet and sets the EnforceConstraints property to true.

[Visual Basic]

' The next line goes into the Declarations section of the module:
' SuppliersProducts is a class derived from DataSet.
Private myDataSet As SuppliersProducts 

Private Sub CreateUniqueConstraint()
   Dim myUC As UniqueConstraint
   myUC  = New UniqueConstraint _
      (myDataSet.Tables("Suppliers"), _
      myDataSet.Tables("Suppliers").Columns("CompanyID"))
End Sub

See Also

UniqueConstraint Members | System.Data Namespace | Constraint | ForeignKeyConstraint | DataRelation | AddKeyConstraint | Constraints