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题解 | #创建一张新表#

建表语句多谢多练 create table user_info_vip( id int(11) not null primary key auto_increment&...

Mysql

2022-03-03

0 284

题解 | #删除记录（三）#

delete from单个删除，truncate table全部删除，drop table直接删除表 truncate table nowcoder_exam_record

Mysql

2022-02-26

0 351

题解 | #删除记录（二）#

limit 5 返回前五行数据 limit 5,10 返回五到十行的数据 delete from exam_record where submit_time is null&nbs***bsp;timestampdiff(minute, s...

Mysql

2022-02-26

0 269

题解 | #删除记录（一）#

timestampdiff(*时间单位*,*起始时间*,*结束时间*) 计算时间差 delete from exam_record where score < 60 and timestampdiff(minute,&...

Mysql

2022-02-26

0 315

题解 | #更新记录（二）#

update exam_record set submit_time = '2099-01-01 00:00:00' , score = 0 where submit_time is&nbs...

Mysql

2022-02-26

0 317

题解 | #插入记录（三）#

replace 等同于 delete where replace into examination_info value (null,9003,'SQL','hard',90,'2021-01-01 00:0...

Mysql

2022-02-25

0 282

题解 | #浙大不同难度题目的正确率#

sql查询优先级 1.from 2.on 3.join 4.where 5.group by 6.having 7.select !!!!!!!!! 8.distinct 9.order by SELECT difficult_le...

Mysql

2022-02-25

0 294

题解 | #统计复旦用户8月练题情况#

if（*判断条件*,*满足返回*,*不满足返回*） count()计数，无论数值多少，计数+1 sum()总数，计算数值总和 select t1.device_id, university, count(...

Mysql

2022-02-25

0 272

题解 | #21年8月份练题总数#

三个where条件都可以满足题目要求 select count(distinct device_id)did_cnt, count(question_id)question_cnt from question_practice_detail where&n...

Mysql

2022-02-25

0 258

题解 | #找出每个学校GPA最低的同学#

窗口函数https://zhuanlan.zhihu.com/p/92654574 select device_id, university, gpa from ( select device_i...

Mysql

2022-02-25

0 343