mysql - 如何在 MySQL 中按月分组并获得结果，即使是对它们没有值(value)的月份

Question

我有payment数据表(MySQL)记录所有付款。我想按日期对所有付款进行分组。实际上我想按月对他们进行分组，以分析他们特定月份的收入是多少。如果特定月份没有付款，我需要将其设置为 0。

这是我的 SQL 代码。

SELECT SUM(p.sub_total) as sold_income , month(p.invoice_date) as income_month ,MONTHNAME(p.invoice_date) as month_name, YEAR(p.invoice_date) as income_year FROM payment p where (p.invoice_date BETWEEN '2018-01-01' AND '2018-08-01') GROUP BY DATE_FORMAT(p.invoice_date, '%Y%m')

从这段代码中，我得到以下输出:

我在“2018-01-01”和“2018-08-01”之间搜索。所以应该有7个月和7个结果。如果第 1 个月(一月)没有付款，我想要 sold_income = 0 ;

我该怎么做？请帮助我......

Answer 1

生成日期并与此表格连接并预测结果

  SELECT SUM(p.sub_total) as sold_income , month(C_date ) as income_month ,MONTHNAME(C_date ) as month_name, YEAR(C_date ) as income_year from    

           (
                select * from 
                (select adddate('1970-01-01',t4*10000 + t3*1000 + t2*100 + t1*10 + t0) C_date from
                 (select 0 t0 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
                 (select 0 t1 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
                 (select 0 t2 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
                 (select 0 t3 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
                 (select 0 t4 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4) v
                where C_date between '2017-08-01' and '2018-12-31'
                ) All_date
    left join  payment p on on date(p.invoice_date )=All_date.C_date
    where C_date 
    BETWEEN '2017-08-01' AND '2018-08-01'
    GROUP BY income_month ,month_name,income_year