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SQL专项练习

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全部文章（共149篇）

SQL60题解|#从Customers表中检索所有的 ID# 来自专栏

SELECT cust_id FROM Customers;

2023-10-11

0 325

SQL39题解 | #21年8月份练题总数# 来自专栏

#练习总题数: COUNT(questiono_id) #八月份练习总题数:SUM( IF( YEAR(date)=21 AND MONTH(DATE) = 8, 1 ,0)) SELECT COUNT(DISTINCT device_id) AS did_cnt, COUNT(q...

2023-10-11

0 260

SQL38题解 | #查找后降序排列# 来自专栏

SELECT device_id, gpa, age FROM user_profile ORDER BY gpa DESC, age DESC;

2023-10-11

0 278

SQL37题解 | #查找后多列排序# 来自专栏

SELECT device_id, gpa, age FROM user_profile ORDER BY gpa, age;

2023-10-11

0 381

SQL36题解 | #查找后排序# 来自专栏

SELECT device_id, age FROM user_profile ORDER BY age;

2023-10-11

0 575

SQL35题解 | #浙大不同难度题目的正确率# 来自专栏

#做的总题目: COUNT(QPD.question_id) #正确题目: SUM( IF( result = 'right', 1, 0) ) #内链接： # SELECT QD.difficult_level, # (SUM( IF( result = 'right', 1,...

2023-10-11

0 281

SQL34题解 | #统计复旦用户8月练题情况# 来自专栏

#八月份做题个数:SUM( IF( MONTH(date) = 8, 1, 0) ) #八月份做对题个数:SUM( IF( MONTH(date) = 8 AND result = 'right', 1 ,0) ) SELECT UP.device_id, UP.university, ...

2023-10-11

0 659

SQL33题解 | #找出每个学校GPA最低的同学# 来自专栏

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

2023-10-11

0 421

SQL32题解 | #截取出年龄# 来自专栏

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(profile, ',', -2), ',', 1) AS age, count(*) AS number FROM user_submit GROUP BY age;

2023-10-11

0 413

SQL31题解 | #提取博客URL中的用户名# 来自专栏

SELECT device_id,SUBSTRING_INDEX(blog_url, '/', -1) AS user_name FROM user_submit;

2023-10-11

0 262