mysql - 即使没有该月的记录，如何从查询中获取所有月份？

Question

我有一个查询来获取一年中各月份的所有收入总和，但我想从没有记录的月份中获取零，我可以从查询中执行此操作吗？

这是我现在的查询:

$monthRevenueData = \CompanySubscription::selectRaw('SUM(billed_amount) as revenue, MONTHNAME(payment_date) as Month')
    ->groupBy(\DB::raw("YEAR(payment_date)"),\DB::raw("MONTH(payment_date)"))
    ->orderBy(\DB::raw("MONTH(payment_date)"))->get();

输出:

Month    revenue 
January  2000 
August   3000 
october  1000 

即使该月没有记录，我也希望剩余月份的结果为 0。

Answer 1

使用 CTE 来规避此问题。

with allmonths as (
  select 'January' month, 
  union
  select 'February' month
  union 
  select ... 
)
select * from yourtable y, allmonths x
 where x.month = month(y.datefield);

或者你可以使用 -

select COALESCE(your_table.revenue,0), allmonths.month from (
  select 'January' month, 
  union
  select 'February' month
  union 
  select ... 
) as allmonths
LEFT JOIN your_table on month(your_table.datefield) = allmonths.month;

MySQL CTE - https://dev.mysql.com/doc/refman/8.0/en/with.html