0
@@ -0,0 +1,54 @@
0
+Today I was thinking aloud about [Tree Regular Expressions](http://research.microsoft.com/Users/luca/Slides/2003-11-13%20Transitions%20in%20Programming%20Models%20\(Lisbon\).pdf) and how they might make a nice query language for document databases like CouchDB. Someone pointed out that CSS3 selectors might make a great concrete syntax for this. One thing lead to another and I thought, why not build a relational database in HTML? So I did. I even got **inner joins** working.
0
+
0
+Let's start with a few tables:
0
+
0
+    <table class="users">
0
+      <tr>
0
+        <td class="id">1</td>
0
+        <td class="first_name">amy</td>
0
+        <td class="last_name">bobamy</td>
0
+      </tr> 
0
+      ...
0
+    </table>
0
+    <table class="photos">
0
+      <tr>
0
+        <td class="id">1</td>
0
+        <td class="user_id">1</td>
0
+        <td class="url">http://www.example.com/foo.png</td>
0
+      </tr> 
0
+    </table>
0
+
0
+Now we can express some queries:
0
+
0
+    $('.users')
0
+      .where('.id:eq(1)')
0
+      .select('*')
0
+
0
+This is equivalent to `SELECT * FROM users WHERE id = 1`
0
+
0
+    $('.users')
0
+      .where('.id:eq(1)')
0
+      .select('.id, .name')
0
+
0
+This is equivalent to `SELECT id, name FROM users WHERE id = 1`. Here is something slightly more complicated:
0
+
0
+    $('.users')
0
+      .where('.name:contains(a)')
0
+        .and('.name:contains(c)')
0
+      .select('*')
0
+
0
+But here is **the crowning glory**, the inner join:
0
+
0
+    $('.users')
0
+      .join('.photos')
0
+      .where('.photos.user_id:eq(.users.id)')
0
+        .and('.users.id:eq(1)')
0
+      .select('.photos.url')
0
+
0
+This is equivalent to:
0
+
0
+    SELECT photos.url FROM users, photos
0
+    WHERE photos.user_id = users.id
0
+      AND users.id = 1
0
+      
0
+[Download the fun](http://github.com/nkallen/jquery-database/tree/master) at Github.
0
\ No newline at end of file