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全部文章 / 题解（共21篇）

题解 | #删除表#

drop table if exists exam_record_2011; drop table if exists exam_record_2012; drop table if exi...

Mysql

2021-10-21

1 404

题解 | #修改表#

ALTER TABLE user_info ADD COLUMN school VARCHAR (15) AFTER LEVEL; ALTER TABLE user_info C...

Mysql

2021-10-21

1 504

题解 | #删除记录（四）#

CREATE TABLE user_info_vip ( id INT (11) PRIMARY KEY auto_increment comment "自增ID", uid INT (11) not n...

Mysql

2021-10-20

7 892

题解 | #删除记录（二）#

DELETE FROM exam_record WHERE ( timestampdiff( MINUTE, start_time, submit_time ) < 5 OR submit_time IS NU...

Mysql

2021-10-20

1 596

题解 | #删除记录（一）#

DELETE FROM exam_record WHERE timestampdiff( MINUTE, start_time, submit_time )<5 AND score < 60 timestampdiff 查询两个时间以第一...

Mysql

2021-10-20

16 1214

题解 | #更新记录（二）#

update exam_record set submit_time="2099-01-01 00:00:00", score=0 where score is null ...

Mysql

2021-10-20

2 672

题解 | #插入记录（二）#

INSERT INTO exam_record_before_2021 ( uid, exam_id, start_time, submit_time, score ) SELECT uid, exam_id, start_time, sub...

Mysql

2021-10-20

0 300

题解 | #插入记录（一）#

INSERT INTO exam_record VALUES ( 1, 1001, 9001, "2021-09-01 22:11:12", "2021-09-01 23:01:12", 90 ), ( 2, 1002, ...

Mysql

2021-10-20

1 328

题解 | #浙大不同难度题目的正确率#

SELECT difficult_level, sum(if(result="right",1,0))/count(*) as correct_rate from user_...

Mysql

2021-10-20

0 276

题解 | #统计复旦用户8月练题情况#

select a.device_id, university, sum(if(month(date)=8,1,0)) as ...

Mysql

2021-10-20

0 333