题目 : https://www.nowcoder.com/practice/215a2391bfec4abca05c94812d94da83?tpId=341
数据
drop table if exists questions_pass_record_detail;
CREATE TABLE `questions_pass_record_detail` (
`user_id` int NOT NULL,
`question_type` varchar(32) NOT NULL,
`device` varchar(14) NOT NULL,
`pass_count` int NOT NULL,
`date` date NOT NULL);
INSERT INTO questions_pass_record_detail VALUES(101, 'java', 'app', 2, '2020-03-01');
INSERT INTO questions_pass_record_detail VALUES(102, 'sql', 'pc', 15,'2021-07-07');
INSERT INTO questions_pass_record_detail VALUES(102, 'python', 'pc', 9, '2021-04-09');
INSERT INTO questions_pass_record_detail VALUES(104, 'python', 'app', 3,'2022-03-17');
INSERT INTO questions_pass_record_detail VALUES(105, 'sql', 'pc', 60, '2016-08-15');
INSERT INTO questions_pass_record_detail VALUES(204, 'sql', 'pc', 20, '2019-05-15');
需求
计算单次平均刷题数 , 并命名 : avgCnt
(一条记录数据表示一次刷题)
查询结果 :
avgCnt
18.1667
解决
注意 :
- avg 求平均值
- 一般配合
round(avg(), 2)
使用 , 限制小数点
select
avg(pass_count) as avgCnt
from questions_pass_record_detail;