title: how to add a datetimefield to admin changelist's search_fields
body: <p>In a model's changelist page on admin, I added a DateTimeField "birth" to search_fields.</p>
  
  <pre><code>class DataLog(models.Model):
      id = models.AutoField(primary_key=True, verbose_name="idd")
      birth = models.DateTimeField(auto_now_add=True, verbose_name="create_time") 
  
  class DataLogAdmin(admin.ModelAdmin):
      search_fields = ['id', 'birth', ]
  </code></pre>
  
  <p>it works well when i add it. But a error comes out today:</p>
  
  <pre><code>Warning at /admin/data/log/
      Incorrect datetime value: '%2011-07-12%' for column 'birth' at row 1
      Django Version:     1.2.3
      Exception Location: /usr/lib/python2.5/warnings.py in warn_explicit, line 102
  </code></pre>
  
  <p>this is the db sql:</p>
  
  <pre><code>u'SELECT COUNT(*) FROM `data_log` WHERE (`data_log`.`id` LIKE %2011-07-12% OR `data_log`.`birth` LIKE %2011-07-12% )'
  </code></pre>
  
  <p>I'v edited my django's project a lot since then. </p>
  
  <p>so i dont know what cause this.</p>
  
  <p>here is my question:</p>
  
  <ul>
  <li>insert a DatetimeField to search_fields supported by django? </li>
  <li>what's the correct way to do this? </li>
  <li>any idea about my error?</li>
  </ul>
  
  <hr>
  
  <p><strong>New progress:</strong></p>
  
  <p>I tested that sql.</p>
  
  <p>In Mysql, it runs well. ( both mysql's commandline and Django's dbshell )</p>
  
  <pre><code>mysql&gt; SELECT COUNT(*) FROM `data_log` WHERE (`data_log`.`id` LIKE '%07-19%' OR `data_log`.`birth` LIKE '%07-19%' );
  +----------+
  | COUNT(*) |
  +----------+
  |        3 | 
  +----------+
  1 row in set, 1 warning (0.00 sec)
  </code></pre>
  
  <p>but in django shell, the same error:</p>
  
  <pre><code>User.objects.raw("SELECT COUNT(*) FROM `data_log` WHERE (`data_log`.`id` LIKE '%%07-19%%' OR `data_log`.`birth` LIKE '%%07-19%%' )")[0]
  
  Traceback (most recent call last):
   File "&lt;console&gt;", line 1, in &lt;module&gt;
   File "/usr/lib/python2.5/site-packages/django/db/models/query.py", line 1379, in __getitem__
     return list(self)[k]
   File "/usr/lib/python2.5/site-packages/django/db/models/query.py", line 1372, in __iter__
     for row in self.query:
   File "/usr/lib/python2.5/site-packages/django/db/models/sql/query.py", line 73, in __iter__
     self._execute_query()
   File "/usr/lib/python2.5/site-packages/django/db/models/sql/query.py", line 87, in _execute_query
     self.cursor.execute(self.sql, self.params)
   File "/usr/lib/python2.5/site-packages/django/db/backends/util.py", line 15, in execute
     return self.cursor.execute(sql, params)
   File "/usr/lib/python2.5/site-packages/django/db/backends/mysql/base.py", line 86, in execute
     return self.cursor.execute(query, args)
   File "/var/lib/python-support/python2.5/MySQLdb/cursors.py", line 168, in execute
     if not self._defer_warnings: self._warning_check()
   File "/var/lib/python-support/python2.5/MySQLdb/cursors.py", line 82, in _warning_check
     warn(w[-1], self.Warning, 3)
   File "/usr/lib/python2.5/warnings.py", line 62, in warn
     globals)
   File "/usr/lib/python2.5/warnings.py", line 102, in warn_explicit
     raise message
  Warning: Incorrect datetime value: '%07-19%' for column 'birth' at row 1
  </code></pre>