Question

I have a DB schema from The Data Model Resource Book, Vol. 1. In it is a table like this:

CREATE TABLE [dbo].[AccountingPeriod](
  [AccountingPeriodID] [int] NOT NULL,
  [RoleTypeID] [int] NOT NULL,
  [PeriodTypeID] [int] NOT NULL,
  [AcctgPeriodNum] [int] NOT NULL,
  [FromDate] [smalldatetime] NOT NULL,
  [ThruDate] [smalldatetime] NOT NULL,
  [PartyID] [int] NOT NULL,
PRIMARY KEY CLUSTERED (
  [AccountingPeriodID] ASC)

With a constraint defined as:

ALTER TABLE [dbo].[AccountingPeriod]  WITH CHECK ADD FOREIGN KEY([AccountingPeriodID])
REFERENCES [dbo].[AccountingPeriod] ([AccountingPeriodID])

The AccountingPeriodID column has a self referencing foreign key that the text claims is a recursive reference column but I think it’s an error. I think I need another column to properly store recursive references in this table. Can the author’s method be implemented with the table definition supplied, why?

Answer 1

Yes, You need another column which will reference the primary key column of the table itself, for self referencing a table. Self referencing column really does not make any sense.