摘要：知识点 sum(cost) over(PARTITION BY NAME ORDER BY p_date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS sample4,--和sample3一样,由起点到当前行的聚合 sum(cost) ov 阅读全文

摘要：方法一：自连接（我自己想到的） # select a.employee_id # from Employees a # left join Employees b # on a.manager_id=b.employee_id # left join Employees c # on b.manag 阅读全文

摘要：方法一：我自己写的 # with t as # ( # select * # ,case when host_goals>guest_goals then 3 when host_goals=guest_goals then 1 else 0 end as host_score, # case wh 阅读全文

摘要：方法一 select round(sum(case when order_date=customer_pref_delivery_date then 1 else 0 end)/count(*)*100,2) immediate_percentage from Delivery; 方法二 selec 阅读全文