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题解 | #统计作答次数#

select count(*) total_pv, sum(case when submit_time is null then 0 else 1 end) complete_pv, count(distinct...

2023-10-06

0 199

题解 | #SQL类别高难度试卷得分的截断平均值#

select t2.tag, t2.difficulty, round(avg(t1.score),1) clip_avg_score from exam_record t1 left join examination_info t2 on t1....

2023-10-05

0 374

题解 | #删除索引#

alter table examination_info drop index uniq_idx_exam_id, drop index full_idx_tag;

2023-10-05

0 234

题解 | #创建索引#

alter table examination_info add index idx_duration (duration), add unique index uniq_idx_exam_id (exam_id), add fulltext index full_idx_tag (tag);

2023-10-05

1 403

题解 | #删除表#

drop table exam_record_2012,exam_record_2013,exam_record_2014

2023-10-05

0 214

题解 | #鸢尾花分类_2#

from sklearn import datasets from sklearn.model_selection import train_test_split from sklearn import metrics from sklearn.naive_bayes import Gaussian...

2023-10-04

1 309

题解 | #鸢尾花分类#

from sklearn import datasets from sklearn import metrics from sklearn.model_selection import train_test_split from sklearn import svm def train_and_...

2023-10-04

0 398

题解 | #修改表#

alter table user_info drop column job, modify column achievement int(11) Default 0, add column school varchar(15) after level, add ...

2023-10-04

0 185

题解 | #创建一张新表#

create table user_info_vip( id int(11) not null primary key auto_increment comment '自增ID', uid int(11) not null unique comment '用户ID', ni...

2023-10-04

0 204

题解 | #删除记录（二）#

delete from exam_record where timestampdiff(minute,start_time,submit_time) < 5 or submit_time is null order by start_time limit ...

2023-10-04

1 231