LC 1479. 周内每天的销售情况

link

select i.item_category as category, 

sum(if(date_format(order_date,'%W')='Monday',quantity,0)) as 'Monday',
sum(if(date_format(order_date,'%W')='Tuesday',quantity,0)) as 'Tuesday',
sum(if(date_format(order_date,'%W')='Wednesday',quantity,0)) as 'Wednesday',
sum(if(date_format(order_date,'%W')='Thursday',quantity,0)) as 'Thursday',
sum(if(date_format(order_date,'%W')='Friday',quantity,0)) as 'Friday',
sum(if(date_format(order_date,'%W')='Saturday',quantity,0)) as 'Saturday',
sum(if(date_format(order_date,'%W')='Sunday',quantity,0)) as 'Sunday'
from orders o right join items i on o.item_id=i.item_id 
group by i.item_category
order by item_category