Sql Foreign Key Constraint

[Wasabi]

Hi,

 

Is the an advantage to declaring foreign keys with the following syntax?

 

CREATE TABLE Orders
(
O_Id int NOT NULL,
OrderNo int NOT NULL,
P_Id int,
PRIMARY KEY (O_Id),
CONSTRAINT fk_PerOrders FOREIGN KEY (P_Id)
REFERENCES Persons(P_Id)
)

 

Many Thanks!

[Larry]

Perhaps, depending upon the version of MySQL and the storage engine in use, neither of which do you mention.

[Wasabi]

Perhaps, depending upon the version of MySQL and the storage engine in use, neither of which do you mention.

 

MySQL 5.5.9

With A myISAM Storage engine.

 

Just saw the syntax at W3 Schools and was applying the question to the book examples.

 

As always Many Thanks!

[HartleySan]

When you say syntax, do you mean the statements used, or perhaps the order of declarations, or perhaps the actual names used? Please let us know.

[Wasabi]

Please pardon the vagueness. I'm interested in grasping the

advantage, if any, in using these statements.

 

CONSTRAINT fk_PerOrders FOREIGN KEY (P_Id)
REFERENCES Persons(P_Id)

[Larry]

If you're using a MyISAM table, there is no advantage as MyISAM does not support foreign key constraints.

[Wasabi]

Thanks Larry,

 

That bit of information, using foreign key constraints with a myISAM

engine was omitted from the example at W3Schools.

[Larry]

And that, of course, is why it's important to include all the relevant details when you ask a question here. A note I've given you on several occasions, I believe.

[Wasabi]

Correct, you have. I also reviewed that suggestion

in the chapter on Debugging, and Will include

 

PHP Version

mySQL Version

Engine Information

OS Version

 

In all future post.