sql训练小白

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题解 | 推荐内容准确的用户平均评分

select avg(distinct score) avg_score from user_action_tb a join recommend_tb b on a.user_id = b.rec_user where a.hobby_l = b.rec_info_...

2026-02-03

0 67

题解 | 查询培训指定课程的员工信息

select ct.staff_id, st.staff_name from staff_tb st left join cultivate_tb ct on st.staff_id = ct.staff_id where ct.course like '%c...

2026-02-03

0 74

题解 | 统计所有课程参加培训人次

select sum( CASE WHEN course IS NULL OR course = '' THEN 0 ELSE LENGTH(course) - LENGTH(REPLACE(course, ',', '')) + 1 E...

2026-02-03

0 79

题解 | 分析客户逾期情况

SELECT t2.pay_ability, CONCAT( ROUND(COALESCE(t1.overdue_cnt, 0) * 100.0 / t2.total_cnt, 1), '%' ) AS overdue_ratio FROM...

2026-01-22

0 50

题解 | 最长连续登录天数

WITH raw_data AS ( SELECT DISTINCT user_id, fdate FROM tb_dau WHERE fdate BETWEEN '2023-01-01' AND '2023-01-31' ), grouped AS ( SELECT ...

2026-01-14

0 127

题解 | 每个月Top3的周杰伦歌曲

WITH raw_data AS ( SELECT pl.fdate, si.song_name FROM user_info ui INNER JOIN play_log pl ON pl.user_id = ui.user_id ...

2026-01-14

0 173