mysql - 我需要使用 group by 和汇总的查询帮助

Question

我正在尝试在第一列中显示订单年份，在第二列中显示月份。另外，按月和按年显示总计以及总计。此外，显示消息“年度总计”和“总计”而不是空值。结果按年和月排序。

我不断收到错误消息（“字段列表”中的未知列“order_date”）有人可以帮助我吗？

 select coalesce(year(order_date), 'Grand Total') as Year
, case when year(order_date) is null then ' ' else coalesce(month(order_date), 'Year Total') end as 
Month 
, AmntDue 
, NumberOfBooksPurch  
from (    
     select   year(order_date) as Year 
            , month(order_date) as Month
            ,  sum(quantity * order_price) as AmntDue    
            ,  count(order_id) as NumberOfBooksPurch    
            from a_bkorders.order_headers   
            join a_bkorders.order_details using (order_id)       
            group by year(order_date), month(order_date), order_id with rollup
     ) tbl;

Answer 1

order_date是原始表中的一个值，但子查询没有返回它，因此您不能在外部查询中引用它。使用子查询返回的别名：

select coalesce(Year, 'Grand Total') as Year
, case when Year is null then ' ' else coalesce(Month, 'Year Total') end as 
Month 
, AmntDue 
, NumberOfBooksPurch  
from (    
     select   year(order_date) as Year 
            , month(order_date) as Month
            ,  sum(quantity * order_price) as AmntDue    
            ,  count(order_id) as NumberOfBooksPurch    
            from a_bkorders.order_headers   
            join a_bkorders.order_details using (order_id)       
            group by Year, Month, order_id with rollup
     ) tbl;