使用两个顺序的codeigniter活动记录查询

Question

I'm new in CI, and I have a question..

My normal sql is:

$tb1 = 'se_avg';
$tb2 = 'se_school';

$sql_top = "(SELECT * FROM $tb1 ,$tb2 WHERE $tb1.sid = $tb2.sid AND gid = '$gid' AND avg_mark > $s_mark  AND $tb1.year = '2014' ORDER BY avg_mark ASC LIMIT 0 , 20) ORDER BY vg_mark DESC";

I wanna rewrite it in CI active record.

But I have no idea to put another order by outside this sql：

$sql_top = "(SELECT * FROM $tb1 ,$tb2 WHERE $tb1.sid = $tb2.sid AND gid = '$gid' AND avg_mark > $s_mark  AND $tb1.year = '2014' ORDER BY avg_mark ASC LIMIT 0 , 20)

Now, my CI active record is:

$tb1 = 'se_avg';
$tb2 = 'se_school';

$sql_top = $this->db
           ->select('*')
           ->from($tb1)
           ->join($tb2, "$tb1.sid = $tb2.sid", 'left')
           ->where('gid', $gid)
           ->where('avg_mark >', $s_mark)
           ->where("$tb1.year", '2014')
           ->order_by("avg_mark", 'asc')
           ->limit(20, 0);

$query = $this->db->get();

Where can I add order_by(("avg_mark", 'desc')?

I've try to put it after limit, but I get wrong data...

Maybe there's another way?

Thanks!

Answer 1

• make the following changes in the query and you will get the desired result
• change which table contains avg_mark
  

->order_by('$tb1.avg_mark', 'DESC')