On Mon, 4 Nov 2002 15:38:50 -0600, Charles Parks wrote: >What is the difference between a foreign key and the rule verify a value >exists?
RULES can be turned off, FKs cannot. (This is both a plus and a minus.) Constraints are checked more rapidly than rules. A PK/FK pair does the same work as a BUNCH of rules: "Require a value," "Require a unique value", "verify a value", and "delete restriction" There is no way with rules alone that you can prevent the update of a primary key referenced by a foreign key. RULES are more flexible and powerful. Almost anything you can do in a WHERE clause you can do in a rule. Bill ================================================ TO SEE MESSAGE POSTING GUIDELINES: Send a plain text email to [EMAIL PROTECTED] In the message body, put just two words: INTRO rbase-l ================================================ TO UNSUBSCRIBE: send a plain text email to [EMAIL PROTECTED] In the message body, put just two words: UNSUBSCRIBE rbase-l ================================================ TO SEARCH ARCHIVES: http://www.mail-archive.com/rbase-l%40sonetmail.com/
