Drupal 7 special chars not working in db_select
It doesn't look like anything wrong with query. I'm using drupal 7 with basic setup and one node(nid=3) has 24/7 in title &amp; body and one node(nid=4) has only in body.

  // Make sure to decode, if the search string is part of URL.
  // $search_text = urldecode($_GET['query']);

  $search_text = '24/7';
  $query = db_select('node', 'n');
  $query-&gt;join('field_data_body', 'b', 'b.entity_id=n.nid');
  $query-&gt;fields('n', array('nid'))
    -&gt;condition(db_or()
    -&gt;condition('n.title', '%' . db_like($search_text) . '%', 'LIKE')
    -&gt;condition('b.body_value', '%' . db_like($search_text) . '%', 'LIKE')
  );
  $result = $query-&gt;execute()-&gt;fetchAll();
  print_r(db_like($search_text));
  print_r($query-&gt;arguments());
  print_r($result);


and the result is:

// print_r(db_like($search_text));
24/7

// print_r($query-&gt;arguments());
Array
(
    [:db_condition_placeholder_0] =&gt; %24/7%
    [:db_condition_placeholder_1] =&gt; %24/7%
)

// print_r($result);
Array
(
    [0] =&gt; stdClass Object
        (
            [nid] =&gt; 2
        )

    [1] =&gt; stdClass Object
        (
            [nid] =&gt; 3
        )

)


Note: If you are getting the search string from URL as query string make sure, you have done urldecode() before send to SQL.