protected virtual void AddClicked(object sender, EventArgs e)
        {
            ForeignKeyConstraintSchema fk = schemaProvider.CreateForeignKeyConstraintSchema(string.Concat(table.Name,
                                                                                                          "_",
                                                                                                          "fk_new"));
            int index = 1;

            while (constraints.Contains(fk.Name))
            {
                fk.Name = string.Concat(table.Name, "_", "fk_new", (index++).ToString());
            }

            constraints.Add(fk);
            AddConstraint(fk);
            EmitContentChanged();
        }