A Practical Approach to Object-Relational Mapping in PHP Page 5

Let’s look at some options.

Option 1: Repeating Code

The easiest way to implement ArmedHippo’s RDB methods is to first add a new column to the hippos table:

Field	Type	Notes
id	integer	Primary key Auto increment
name	text
num_mount_points	integer

Then we can cut-and-paste Hippo::load() and Hippo::save()
into ArmedHippo, and add the num_mount_points field.

<?php
//ArmedHippo methods
function load($id) {
    $this->id = $id;
    $conn = mysql_connect('localhost', 'hippo_user', 'hippo_user');
    mysql_select_db('hippos');
    $result = mysql_query("select name,
    num_mount_points from hippos where id=$id");
    $this->name = mysql_result($result, 0, 'name');
    $this->num_mount_points =  mysql_result($result, 0, 'num_mount_points');
    application_utility_tasks();
}
function save() 
{
    $conn = mysql_connect('localhost', 'hippo_user', 'hippo_user');
    mysql_select_db('hippos');
    if ( is_null($this->id) ) 
    {
        //New record
        $query = "insert into hippos (name, num_mount_points)
        values ('".$this->name."', ".
        $this->num_mount_points.")";
        mysql_query($query);
        $this->id = mysql_insert_id();
    }
    else 
    {
        //Update existing record
        $query = "update hippos set name='".$this->name."',
        num_mount_points=".$this->num_mount_points."
        where id=".$this->id;
        mysql_query($query);
    }
    application_utility_tasks();
}
?>

The save() method looks at the id property on line 15. If id is null, the method adds a new
record, and gets the id number allocated to it by MySQL on line 21. If id is not null,
save() uses it an a primary key value in an SQL UPDATE statement (line 25).

This will work, but loses some of the advantages of OOP. If we add a weight property to Hippo, we’ll
also need to change ArmedHippo::load() and ArmedHippo::save().
If we add StealthHippo, we’ll introduce more code that needs to be changed as Hippo changes.
Further, all versions of the load() and save()
methods call application_utility_tasks() separately. If we need to change the call, the code must be
updated in every place.