UniqueConstraint serializable

UniqueConstraint

serializable

---

System.Data (system.data.dll)

class

The UniqueConstraint is a rule that prevents duplicate values in a column. There are two ways to create a UniqueConstraint : by setting the DataColumn.Unique property to true for one or more columns , or by using the IDataAdapter.FillSchema( ) method when retrieving a row set that includes a primary key column. You could also create a UniqueConstraint object using the new keyword, however, you need to add it to the DataTable.Constraints collection before it takes effect; simply specifying the column and table information isn't enough. As with all constraints, the UniqueConstraint is enforced only when the DataSet.EnforceConstraints is true (the default).

 public class  UniqueConstraint  : Constraint {  // Public Constructors  public  UniqueConstraint  ( DataColumn   column   );      public  UniqueConstraint  ( DataColumn[ ]   columns   );      public  UniqueConstraint  (DataColumn[ ]   columns   , bool   isPrimaryKey   );    public  UniqueConstraint  (DataColumn   column   , bool   isPrimaryKey   );    public  UniqueConstraint  ( string   name   , DataColumn   column   );      public  UniqueConstraint  (string   name   , DataColumn[ ]   columns   );    public  UniqueConstraint  (string   name   , DataColumn[ ]   columns   , bool   isPrimaryKey   );    public  UniqueConstraint  (string   name   , DataColumn   column   , bool   isPrimaryKey   );    public  UniqueConstraint  (string   name   , string[ ]   columnNames   , bool   isPrimaryKey   );  // Public Instance Properties  public virtual DataColumn[ ]  Columns  {get; }     public bool  IsPrimaryKey  {get; }     public override DataTable  Table  {get; }  // overrides Constraint   // Public Instance Methods  public override bool  Equals  ( object   key2   );  // overrides object  public override int  GetHashCode  (  );  // overrides object  } 

Hierarchy

System.Object Constraint UniqueConstraint

Returned By

DataRelation.ParentKeyConstraint