MySQL查询失灵？

Question

I have the below MySQL query, which should return the t1.username, t1.website, in_count (WHERE t2.type = 'in'), out_count (WHERE t2.type = 'out') and WHERE the t1.website field is NOT EMPTY or NULL.

However its seemed to have malfunctioned (or I'm doing something wrong?), as it returns 1 result (via mysql_num_rows()) and when i print_r() (on the mysql_fetch_assoc()), the keys of the columns are their however all the values are empty/blank (see below).

The print_r() dump:

Array
(
    [username] => 
    [website] => 
    [in_count] => 
    [out_count] => 
)

The MySQL query:

SELECT t1.username,
       t1.website,
       SUM(IF(t2.type = 'in', 1, 0))  AS in_count,
       SUM(IF(t2.type = 'out', 1, 0)) AS out_count
FROM   users AS t1
       JOIN referrals AS t2
         ON t1.username = t2.author
WHERE  NOT Isnull(t1.website)
LIMIT  0, 10 

Hope all is clear, let me know if you need more information, appreciate all help. :B

Answer 1

Sounds like you might need a GROUP BY clause at the end? Perhaps

GROUP BY t1.username, t1.website

That way you'll get all the in and out counts for a particular user on a particular web site.

I was under the impression that with aggregate functions like SUM the query requires a GROUP BY clause... I'm surprised the server accepted your SQL.