> Unfortunately this goes well beyond the scope of my original question. > Although the inputs that you all have provided thus far have been a very > good read, I still don't grasp the concept of defining a relationship. Is > it simply referring to a primary key in a field other than the one where the > key was defined? Or is there some other way to define a key that I don't > see? All I'm looking for is a simple example, syntax excerpt, etc...that > shows me (only the "slow learner" level) exactly how to define a > relationship.
> Unfortunately this goes well beyond the scope of my original question. > Although the inputs that you all have provided thus far have been a very > good read, I still don't grasp the concept of defining a relationship. Is > it simply referring to a primary key in a field other than the one where the > key was defined? Or is there some other way to define a key that I don't > see? All I'm looking for is a simple example, syntax excerpt, etc...that > shows me (only the "slow learner" level) exactly how to define a > relationship. CREATE TABLE parent ( parent_id INT UNSIGNED NOT NULL PRIMARY KEY ) TYPE=innodb; CREATE TABLE child ( child_id INT UNSIGNED NOT NULL PRIMARY KEY, parent_id INT UNSIGNED NOT NULL, INDEX ( parent_id ), FOREIGN KEY ( parent_id ) REFERENCES parent( parent_id ) ) TYPE=innodb; CREATE TABLE grandchild ( grandchild_id INT UNSIGNED NOT NULL PRIMARY KEY, child_id INT UNSIGNED NOT NULL, INDEX ( child_id ), FOREIGN KEY ( child_id ) REFERENCES child( child_id ) ) TYPE=innodb; To see the relationships at work, try to insert into grandchild a child_id that doesn't exist in child, or try to insert into child a parent_id that doesn't exist in parent. hth PB ----- filter fodder: mysql --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
