SQL Clearly Explained by Jan L. Harrington

Author:Jan L. Harrington
Language: eng
Format: epub, pdf
ISBN: 978-0-12-375697-8
Publisher: Elsevier Science
Published: 2010-05-25T16:00:00+00:00

Because the SET CONSTRAINT MODE statement requires a named constraint, it cannot be applied to constraints created within a CREATE TABLE statement unless those constraints have been named. This means that if you want to have control over when the checking of such constraints occurs, you need to add a CONSTRAINT clause to the table declaration so you have somewhere to name a constraint.

As an example, consider the table declaration in Figure 9-5. The addition of the CONSTRAINT clause allows both the primary and foreign keys to be named, making them accessible to a SET CONSTRAINTS MODE statement (although the primary key has been specified as not deferrable.)

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