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题解 | 插入记录（三）

REPLACE INTO examination_info VALUES (NULL,9003,"SQL","hard",90,"2021-01-01 00:00:00")

2025-06-28

0 68

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,submit_time,score FROM exam_record WHERE ...

2025-06-28

0 53

题解 | 插入记录（一）

INSERT INTO exam_record VALUES(NULL,1001,9001,"2021-09-01 22:11:12","2021-09-01 22:11:12"+INTERVAL 50 MINUTE,90 ), (NULL...

2025-06-28

0 46

题解 | 基本数学函数

SELECT *, ABS(value) AS absolute_value, CEIL(value) AS ceiling_value, FLOOR(value) AS floor_value, ROUND(value,1) AS rounded_valu...

2025-06-27

0 63

题解 | 计算每日累计利润

SELECT * ,SUM(profit) OVER(ORDER BY profit_date) AS cumulative_profit FROM daily_profits;

2025-06-27

0 82

题解 | 电话号码格式校验

SELECT id,name,phone_number FROM contacts WHERE phone_number REGEXP "^[1-9][0-9]{9}$" OR phone_number REGEXP "^[1-9][0-9]{2}-[0-9]{3}-[...

2025-06-27

0 58

题解 | 浙大不同难度题目的正确率

SELECT t3.difficult_level, COUNT(CASE WHEN t2.result="right" THEN t2.question_id ELSE NULL END)/COUNT(t2.question_id) AS correct_rate...

2025-06-27

0 63

题解 | 统计复旦用户8月练题情况

SELECT t1.device_id,t1.university, COUNT(t2.question_id) AS question_cnt, COUNT(CASE WHEN t2.result="right" THEN t2.question_i...

2025-06-27

0 50

题解 | 找出每个学校GPA最低的同学

SELECT device_id,university,gpa FROM user_profile WHERE (university,gpa) IN (SELECT university, MIN(gpa) FROM user_profile GROUP B...

2025-06-27

0 67

题解 | 截取出年龄

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(profile,",",-2),",",1) AS age, COUNT(device_id) AS number FROM user_submit GROUP BY...

2025-06-27

0 77