哈喽.沃德

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题解 | #纠错4#

SELECT cust_name, cust_contact, cust_email FROM Customers WHERE cust_state = 'MI' UNION SELECT cust_name, cust_contact, cust_email FRO...

Mysql

2022-05-16

0 288

题解 | #提取博客URL中的用户名#

从最后一个 / 处截取字符串 substring_index函数 select us.device_id,substring_index(us.blog_url,'/',-1) as user_name from user_submit us 替换掉前面的字符串 replace()函数 ...

Mysql

2022-04-29

13 521

题解 | #浙江大学用户题目回答情况#

select substring_index(us.profile,',',-1) as gender,count(*) number from user_submit us group by gender; 函数：根据index截取字符串 substring_index(str,del...

Mysql

2022-04-29

0 255

题解 | #浙江大学用户题目回答情况#

select date_format(qpd.date,'%d') as day,count(*) as question_cnt from question_practice_detail qpd where date_format(qpd.date,'%Y-%m') = '2...

Mysql

2022-04-29

1 289