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全部文章（共32篇）

题解 | 试卷发布当天作答人数和平均分

SELECT ei.exam_id, count(distinct er.uid) AS uv, round(AVG(er.score),1) AS avg_score FROM exam_record er LEFT JOIN user_info ui ON er....

2026-01-24

0 59

题解 | 月总刷题数和日均刷题数

-- 2021 每月 + 全年（全年分母固定 31） SELECT stat_month, COUNT(*) AS month_q_cnt, ROUND( COUNT(*) / DAY( LAST_DAY( ...

2026-01-24

0 55

题解 | 查找山东大学或者性别为男生的信息

SELECT device_id, gender, age, gpa FROM user_profile WHERE university = '山东大学' UNION ALL SELECT device_id, gender, age, gpa FROM user_profile WHERE ...

2026-01-24

0 62

题解 | 分析客户逾期情况

select c.pay_ability, concat(round(count(l.overdue_days)/count(*)*100,1),'%') overdue_ratio from loan_tb l left join customer_tb c using(customer_id) ...

2026-01-23

0 50

题解 | 查找后多列排序

select device_id, gpa, age from user_profile order by gpa ASC, age ASC;

2026-01-23

0 48

题解 | 计算用户的平均次日留存率

WITH base AS ( SELECT device_id, practice_date, LEAD(practice_date) OVER ( PARTITION BY device_id ...

2026-01-22

0 48

题解 | 计算用户的平均次日留存率

WITH base AS ( SELECT device_id, DATE(date) AS practice_date, RANK() OVER ( PARTITION BY device_id ...

2026-01-22

0 48

题解 | 查询出不同类别商品中，销售金额排名前三且利润率超过 20%的商品信息

WITH product_sales AS ( SELECT t1.product_id, t1.product_name, t1.category_id, SUM(t2.sales_amount) AS sales_amoun...

2026-01-20

0 43

题解 | 得分不小于平均分的最低分

WITH ranked_scores AS ( SELECT t1.score, t2.tag, RANK() OVER ( ORDER BY ...

2026-01-19

0 51

题解 | 每天的日活数及新用户占比

WITH first_login AS ( SELECT uid, MIN(DATE(in_time)) AS first_login_time FROM tb_user_log ...

2026-01-19

0 28