sub queries order by - php

Question

I am trying get records from question order by sub query (qcat) table. and my code is
"SELECT * FROM question
where survey_name='$_SESSION[ssn_sname]' AND
qcategory IN
( SELECT qcategory FROM qcat
WHERE client_name='$_SESSION[ssn_sname]'
GROUP BY qcategory
ORDER BY p_order
) AND
status='1' AND
survey_name LIKE'%$sname%
LIMIT $start, $limit";
But it did not get results in order.
how can i get rows order by the qcat table?

Answer 1

In the sub query you do not need the GROUP BY clause - This is used for aggregated functions
You also do not need the ORDER BY in the sub query - Let mysql work it out for the in bit
Add the ORDER BY for the whole query. i.e. at the end
So the SQL should be
"SELECT * FROM question
where survey_name='$_SESSION[ssn_sname]' AND
qcategory IN
( SELECT qcategory FROM qcat
WHERE client_name='$_SESSION[ssn_sname]'
) AND
status='1' AND
survey_name LIKE'%$sname%
ORDER BY p_order
LIMIT $start, $limit";
I also think that you may be able to avoid the sub query in the first place. But that would require a little thinking and a bit more knowledge about the tables.
BTW - Note the possibility of SQL injection

Answer 2

You need to join with the qcat table in order to be able to sort on a different column within that table. Try this:
$query = "
SELECT q.id question_id, q.*, c.*
FROM question q
INNER JOIN qcat c ON c.category = q.category
WHERE q.survey_name='$_SESSION[ssn_sname]'
AND c.client_name = '$_SESSION[ssn_sname]'
AND q.status='1'
AND q.survey_name like '%$sname%'
GROUP BY q.id
ORDER BY c.p_order
LIMIT $start, $limit";
Note: Your query is vulnerable to SQL Injection!