I'm new to object oriented php. Trying to query database but not getting any results
I won't address your question specifically...because you're doing it wrong, and that should stop here :)

This is very, very bad:

db_query("SELECT * FROM tls_connect_stage_timer WHERE '".$agent."' IN ('start_processing_agent' || 'end_processing_agent')");


You should never concatenate data into an SQL string, you'll leave yourself ripe for injection attacks.  This one is even worse:

db_query("SELECT * FROM tls_active_applicants WHERE `".$searchParams."`='".$input."'");


As you're liable to injection attacks from both the field name and the argument.

If you want to use dynamic field names you should use the SelectQuery class, accessible via db_select(). E.g.

$values = array('start_processing_agent', 'end_processing_agent');
$query = db_select('tls_connect_stage_timer', 't')
  -&gt;fields('t')
  -&gt;condition($field_name, $values);

$rows = $query-&gt;execute()-&gt;fetchAll();


You'll need to make some changes to the above for your specific query, but that's the general idea.