$field='agents_id,users_id,call_type,call_time,time,voice_file,c.user_status,a.id,a.create_time,a.type,secret_no,c.id as user_id';
$field='agents_id,users_id,call_type,call_time,time,voice_file,c.user_status,a.id,a.create_time,a.type,secret_no,c.id as user_id,c.agent_id as c_agent_id';