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POWhat is the difference between a ORM, AR, QB, & DM?
 

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  1. POWhat is the difference between a ORM, AR, QB, & DM?
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    <p>Ok, so everyone has decided (and for good reason) strait SQL is of the devil. This leaves us with many methods of placing a "middle-man" in our code to separate our code from the database. I am now going to spit out all the info I have gathered in the hope someone can set me strait and tell me what I built.</p> <p>An ORM (Object-relational mapping) is a series of tools (loosely or tightly integrated depends) which maps database rows to objects in the application.</p> <p>In an AR (Active-Record) is a type of ORM in which a database table or view is wrapped into a class, thus an object instance is tied to a single row in the table.</p> <p>Data mapping (DM) is a type of ORM that is the process of creating data element mappings between two distinct data models.</p> <p>All three claim to work like this:</p> <pre><code>$user = new User(); $user-&gt;name = 'Fred'; $user-&gt;save(); </code></pre> <p>Usually with a User class something like this:</p> <pre><code>class User extends Model { // Specify the database table protected $table = "users"; // Define your fields protected $fields = array( 'id' =&gt; array('type' =&gt; 'int', 'primary' =&gt; true), 'name' =&gt; array('type' =&gt; 'string', 'required' =&gt; true), 'email' =&gt; array('type' =&gt; 'text', 'required' =&gt; true) ); } </code></pre> <p>With this setup you can easily fetch rows without the need to write SQL.</p> <pre><code>// users $users = $user-&gt;fetch(array('id' =&gt; 3)); </code></pre> <p>Some AR classes actually look more like this:</p> <pre><code>$db-&gt;where('id' =&gt; 3); $db-&gt;join('posts', 'posts.user_id = users.id'); $results = $db-&gt;get('users'); </code></pre> <p>Ok, now this is where it gets hairy. Everyone and his brother seems to have a different view on what type of code falls where. While most agree that an AR or DM is a type of ORM - but sometimes the lines that tell AR's from DM's seem to smear.</p> <p>I wrote a class that uses a single object ($db) in which you make calls to this object and it handles SQL creation for result saving/fetching.</p> <pre><code>//Fetch the users $results = $db-&gt;select('id, name')-&gt;where('id &gt; 4')-&gt;get('users'); //Set them active while($user = $results-&gt;fetch()) { $user-&gt;active = TRUE; $user-&gt;save(); } </code></pre> <p>So the question is "what is it?", and why don't people agree on these terms?</p>
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