This abstract class represents a rule that can be placed on one or more DataColumn objects. ADO.NET includes two derived constraint classes: ForeignKeyConstraint and UniqueConstraint . Constraints aren't enforced unless the EnforceConstraints property of the DataSet is true. public abstract class Constraint { // Protected Constructors protected Constraint ( ); // Public Instance Properties public virtual string ConstraintName {set; get; } public PropertyCollection ExtendedProperties {get; } public abstract DataTable Table {get; } // Protected Instance Properties protected internal virtual DataSet _DataSet {get; } // Public Instance Methods public override string ToString ( ); // overrides object // Protected Instance Methods protected void CheckStateForProperty ( ); protected internal void SetDataSet ( DataSet dataSet ); } SubclassesForeignKeyConstraint , UniqueConstraint Returned ByConstraintCollection.{Add( ) , this} Passed ToConstraintCollection.{Add( ) , AddRange( ) , CanRemove( ) , IndexOf( ) , Remove( )} |