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题解 | #返回顾客名称和相关订单号#

select cust_name,order_num from Customers inner join Orders on Customers.cust_id = Orders.cust_id #group by cust_name order by cust_name,order_num

2023-03-28

5 626

题解 | #计算总和#

select order_num, sum(item_price*quantity) as total_price from OrderItems group by order_num having total_price>=1000 order by order_num

2023-03-28

0 250

题解 | #返回订单数量总和不小于100的所有订单的订单号#

select order_num from OrderItems group by order_num having sum(quantity)>=100 order by order_num count()和sum()的区别注意区分：count()：汇总，但是汇总属性总数即你出现几次就cou...

2023-03-28

0 331

题解 | #每个供应商成本最低的产品#

select vend_id, min(prod_price) as cheapest_item from Products group by vend_id order by cheapest_item

2023-03-28

0 202

题解 | #返回每个订单号各有多少行数#

select order_num, count(order_num) as order_lines from OrderItems group by order_num order by order_lines 对统计数据进行条件输出，需要先将order_num分组，才能分组统计成功

2023-03-28

0 266

题解 | #返回 2020 年 1 月的所有订单的订单号#

select order_num,order_date from Orders where year(order_date)=2020 and month(order_date)=01 order by order_date

2023-03-27

0 211

题解 | #21年8月份练题总数#

SELECT count(distinct device_id) as did_cnt, count(question_id) as question_cnt from question_practice_detail where year(date) = 2021 and month(date) ...

2023-03-26

0 207

题解 | #浙大不同难度题目的正确率#

select qd.difficult_level, sum(if(qpd.result="right",1,0))/count(qpd.question_id) as correct_rate from question_practice_detail as qpd left join user...

2023-03-26

0 309

题解 | #截取出年龄#

#俄罗斯套娃式截取 select substring_index(substring_index(profile,",",3),",",-1) as age, count(*) as number from user_submit group by age

2023-03-26

0 259

题解 | #提取博客URL中的用户名#

select device_id, substring_index(blog_url,"/",-1) as user_name from user_submit

2023-03-26

7 820