Name

IsPrimaryKey [UniqueKeyConstraint only]

Synopsis

bool isPrimaryKey = Constraint.IsPrimaryKey;

Constraint.IsPrimaryKey = isPrimaryKey;

Indicates whether the UniqueKeyConstraint represents the primary key for the table.

Example

You can specify that a UniqueKeyConstraint should represent the primary key when creating the UniqueKeyConstraint by setting the IsPrimaryKey property to true. The following code snippet creates a UniqueKeyConstraint that represents a primary key defined on a first and last name column:

// Create an array with the two columns.

DataColumn[] cols = new DataColumn[] {dt.Columns["LastName"],  

                                      dt.Columns["FirstName"]};



// Create the UniqueConstraint object to represent the primary key.

UniqueConstraint uc = new UniqueConstraint("FullName", cols, true);



// Add the UniqueConstraint to the table.

dt.Constraints.Add(uc);

Note

A primary key is created automatically when you use the DataAdapter.FillSchema( ) method, as long as there is at least one unique column in the query. There can be only one primary key on a DataTable at a time. If you attempt to set a second primary key on a table, the original primary key is downgraded to a unique column.