MySQL query w/ COUNT() and HAVING based on date comparison

Question

I am trying to limit my count results to those that meet a specific criteria. I am currently using a WHERE clause and my output is as expected.

Here is my current query, and as you can see *ads_list* and *ads_cate* records will only be fetched if my WHERE recdate meets the 14 day mark:

$queryCats = "
SELECT ads_cate.cateName, COUNT(ads_list.Title)
FROM
ads_cate
JOIN ads_list ON ads_cate.id = ads_list.category 
WHERE to_days(now())<=(to_days(recdate)+14)
GROUP BY ads_cate.cateName";

I would like all categories and ads retrieved, but counted ONLY when they meet my WHERE clause criteria. I have been using the HAVING with 0 luck like below. Maybe there is a better way?

$queryCats = "
SELECT ads_cate.cateName, ads_list.recdate, COUNT(ads_list.Title)
FROM
ads_cate
JOIN ads_list ON ads_cate.id = ads_list.category 
GROUP BY ads_cate.cateName
HAVING to_days(now())<=(to_days(recdate)+14)";

Answer 1

Try using a LEFT JOIN and make the date test part of the join condition:

SELECT ac.cateName, COUNT(al.Title)
    FROM ads_cate ac
        LEFT JOIN ads_list al
            ON ac.id = al.category 
                AND to_days(now())<=(to_days(al.recdate)+14)
    GROUP BY ac.cateName

Answer 2

This may work:

SELECT ads_cate.cateName, ads_list.recdate, COUNT(CASE WHEN to_days(now())<=to_days((recdate)+14) THEN ads_list.Title ELSE NULL END) AS Title
FROM
ads_cate
JOIN ads_list ON ads_cate.id = ads_list.category 
GROUP BY ads_cate.cateName

Answer 3

将过滤后的计数放入子查询中，然后从类别表中将LEFT JOIN放入子查询中。