codeigniter insert if not exist
function safe_update_batch($table_name,$records,$filter_field)
{
$filters=array();
foreach($records as $record)$filters[]=$record[$filter_field];
$this->db->query("SET SESSION group_concat_max_len=10000000");
$query=$this->db->select("GROUP_CONCAT($filter_field) AS existing_keys",FALSE)->where_in($filter_field, $filters)->get($table_name);
$row=$query->row();
$found_fields=explode(',',$row->existing_keys);
$insert_batch=array();
$update_batch=array();
foreach($records as $record)
{
if(in_array($record[$filter_field],$found_fields))$update_batch[]=$record;
else $insert_batch[]=$record;
}
if(!empty($insert_batch))$this->db->insert_batch($table_name,$insert_batch);
if(!empty($update_batch))$this->db->update_batch($table_name,$update_batch,$filter_field);
}