Zend_Db. Am I required to manually set primary and foreign key when building db table?

As I read J.Gilmore Zend Book (Models section):

class Game extends Zend_Db_Table_Abstract
{
 protected $_primary='id'; //line 4
}

[..]Line 4 identifies the table's primary key.By default the framework will 
presume the primary key is an automatically incrementing integer named id,so 
this line is not necessary [..]

I have a question:

• Do I need to manually set primary 开发者_如何学Goand foreign key while building a table (Ex. in phpmyadmin with something like "PRIMARY KEY (id),FOREIGN KEY (post) REFERENCES users (id) ON DELETE CASCADE")?
• Or I can handle tables relationships and fields nature just by referring to Zend code using $_primary,$_dependentTable,$_referenceMap and so on?

thanks

Luca

Both. Although you can get away with an ORM dealing with relations, the database ensures at low-level those relations are respected. Always let the database do its job as much as possible, it is built for handling relations and preventing data corruption. What if your ORM has a bug?

As a somewhat related example, say you have a field declared as int in database, you are responsible as a developper for making sure you use int's in your queries, but the database enforces that rule at a lower level, protecting your data in case you don`t.

You should define the primary/unique keys and any other indexes properly when you create the table.

After you've done this in 99% of cases Zend_Db will understand what's going on as it's able to read the table metadata and derive the primary key from that.