Mysql 无法计算自联接查询

我有一张结构如下的桌子

+-----------------------+--------------+------+-----+---------+-------+
| Field                 | Type         | Null | Key | Default | Extra |
+-----------------------+--------------+------+-----+---------+-------+
| linq_order_num        | char(32)     | NO   | PRI | NULL    |       |
| order_status_id       | int(11)      | YES  | MUL | NULL    |       |
| order_id              | varchar(100) | YES  |     | NULL    |       |
| item_name             | varchar(120) | YES  |     | NULL    |       |
| item_cost             | float        | YES  |     | NULL    |       |
| custmer_id            | int(11)      | YES  | MUL | NULL    |       |
| order_date_time       | datetime     | YES  |     | NULL    |       |
| order_category        | varchar(120) | YES  |     | NULL    |       |
| ordered_by            | int(11)      | YES  | MUL | NULL    |       |
| linq_shipping_cost    | float        | YES  |     | NULL    |       |
| website_shipping_cost | float        | YES  |     | NULL    |       |
| total_cost            | float        | YES  |     | NULL    |       |
| advance_amount        | float        | YES  |     | NULL    |       |
| website               | varchar(120) | YES  |     | NULL    |       |
| other                 | varchar(120) | YES  |     | NULL    |       |
| rvn                   | int(11)      | YES  |     | NULL    |       |
| received_date         | datetime     | YES  |     | NULL    |       |
| delivered_date        | datetime     | YES  |     | NULL    |       |
| store_id              | int(11)      | YES  | MUL | NULL    |       |
+-----------------------+--------------+------+-----+---------+-------+

因此，每天我都需要找到总订单成本。我可以使用此查询来获得它

select sum(total_cost), date_format(order_date_time,"%Y-%m-%d") from 
       order_item group by date_format(order_date_time,"%Y-%m-%d")

此外，我需要总剩余金额支付的交付日期

select sum(total_cost-advance_amount),date_format(delivered_date,"%Y-%m-%d")
       from order_item group by date_format(delivered_date,"%Y-%m-%d")

并非所有日期都有订单，也并非所有日期都有交货。如果有一天没有订单，则该天的总成本应显示为零，显示的总剩余金额应为该天的（总成本预付金额）之和

有没有办法将上述两个查询合并到一个查询中并得到结果

因此，总结一下某一天的情况： 我需要总和（总成本），其中订单日期时间=d， 我需要总额（总成本-预付款金额），其中交货日期=d 基本上是在寻找这样的表格：

Date            Total Cost          Total Delivery Amounts
d                 500                     2000
d1                0                       900
d2                900                     0 

我尝试使用子查询。问题是它没有显示d1的案例，其中当天的总成本为0

查询：

select
    date_format(order_date_time,"%Y-%m-%d") date,
    sum(total_cost) total,
    sum(advance_amount) advance_amount,
    IFNULL( (select sum(total_cost-advance_amount)
from order_item a 
where date_format(a.delivered_date,"%Y-%m-%d") = date_format(d.order_date_time,"%Y-%m-%d") ),0 ) delivery_amount
from order_item d
group by date_format(order_date_time,"%Y-%m-%d"), delivery_amount

---

您可以将两个查询用作派生表，并在日期将它们联接起来。问题是，您需要一个完整的外部连接，MySQL不支持这种连接。因此，首先需要从两列中提取所有日期

select date(order_date_time) as d from order_item
union
select date(delivered_date)  as d from order_item

在查询中使用左连接

select
    dates.dt,
    coalesce(tc.total_cost, 0),
    coalesce(tm.total_remaining, 0)
from (
    select date(order_date_time) as dt from order_item
    union
    select date(delivered_date)  as dt from order_item
) dates
left join (
     select sum(total_cost) as total_cost, date(order_date_time) as dt
     from order_item
     group by dt
) tc using(dt)
left join (
     select sum(total_cost-advance_amount) as total_remaining, date(delivered_date)
     from order_item
     group by dt
) tm using(dt)

---

我还将日期格式（..）替换为日期（..）。您可以在外部选择或应用程序中设置日期格式。

以后不要使用

descripe

记录表架构。使用

show create table order\u项目

。“描述”对任何人来说几乎都是无用的