Mysql - 仅父类别的递归查询

Question

我有下表类别:

id | desc_cat       | parent_id
19 | Personal       | (null)
20 | Credit Card    | 19
21 | Academy        | 19
22 | Home           | (null)
23 | Water          | 22
24 | Energy         | 22
25 | Rent           | 22

我有一个表，其中包含名为 cashbook 的条目:

id  | value    | category_id | date
177 | 480.55   | 20          | 2016-05-01
178 | 100.00   | 24          | 2016-05-04
179 | 580.00   | 25          | 2016-05-05
180 | 80.00    | 21          | 2016-05-09
181 | 28.00    | 23          | 2016-05-11

我需要在 cashbook 中预约并返回增值和按父类别分组(类似于 null)，例如:

Category-Father | Total
Personal        | 560,55
Home            | 708

你能帮我组装这个查询吗？？我做了一些示例查询递归，但我很迷茫。我的系统是用 PHP (Yii框架)。

更新 1

我这样做了:

select a.desc_category as segment, sum(b.value) as total 
from category as a
inner join category as c on (a.parent_id = c.id_category and c.parent_id is not null)
inner join cashbook as b on (b.category_id = a.id_category)
INNER JOIN user as u ON b.user_id = u.id
WHERE u.id = 29
group by a.desc_category

作为工作:

SELECT y.desc_category as segment, sum( x.value) as total FROM (
SELECT category.id_category, category.desc_category, category.parent_id , c.value AS value
FROM category
INNER JOIN cashbook AS c ON category.id_category = c.category_id )AS x 
INNER JOIN category AS y ON x.parent_id = y.id_category
INNER JOIN user AS u ON y.user_id = u.id
WHERE u.id = 3
GROUP BY y.desc_category

最后，我如何只获得月份和当年？

我试过就是不行:

WHERE u.id = 3 AND MONTH(date) = 05 AND YEAR(date) = 2016

Answer 1

可以通过使用临时表对同一个表和一个组进行内部连接

select sum( x.value), y.desc_cat from (
select category.id, category.desc, category.parent_id , cashbook.value as value
from category
inner join category.id = cashbook.category_id )  as x 
inner join category as y on x.parent_id = y.id
group by y.desc_cat