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题解 | #计算25岁以上和以下的用户数量#

SELECT Case When age < 25 or age is null then '25岁以下' When age >= 25 then '25岁及以上' End age_cut,count(*)number from user_...

2023-03-03

0 177

题解 | #分组过滤练习题#

SELECT university, avg(question_cnt) as avg_question_cnt, avg(answer_cnt) as avg_answer_cnt from user_profile group by university having avg_question_...

2023-03-02

0 191

题解 | #分组计算练习题#

Select gender,university, count(device_id) as user_num, avg(active_days_within_30) as avg_active_days, avg(question_cnt) as avg_question_cnt from user...

2023-03-02

0 177

题解 | #计算男生人数以及平均GPA#

SELECT count(gender) as male_num,avg(gpa) as avg_gpa from user_profile where gender = 'male' 像这样聚合函数和聚合函数之间用，隔开，不要用and

2023-03-02

0 156

题解 | #查找GPA最高值#

Select round(max(gpa),1) from user_profile where university = '复旦大学' 没能想到聚合函数

2023-03-02

0 184

题解 | #查看学校名称中含北京的用户#

select device_id,age,university from user_profile where university like ('北京%') 虽然可以想到like，但是后续的%还是看了题解

2023-03-02

0 172

题解 | #操作符混合运用#

SELECT device_id,gender,age,university,gpa from user_profile where (gpa>3.5 and university in ('山东大学') ) or (gpa>3.8 and university in ('复旦大学'))...

2023-03-02

0 185

题解 | #Where in 和Not in#

select device_id,gender,age,university,gpa from user_profile where university in ('山东大学','北京大学','复旦大学') in想到了，括号没有，万万没想到university打错了

2023-03-02

0 185

题解 | #高级操作符练习(2）#

SELECT device_id,gender,age,university,gpa from user_profile where gpa > 3.7 or university = '北京大学' 同类题，只是换为or

2023-03-02

0 185

题解 | #高级操作符练习(1)#

Select device_id,gender,age,university,gpa from user_profile where gpa>3.5 and gender = 'male' 相同的需要写and连接

2023-03-02

0 141