MySql基本语法及常见错误
文章目录
- 创建表
- 修改表
- 增加数据
- 修改数据
- 删除数据
- 查询数据
- 分页和排序
- 函数
- like子句
- 事务
- 一些表达式
- 错误解决方案
https://www.nowcoder.com/practice/0355033fc2244cdaa09b2bd6e794c762?tpId=199&tags=&title=&difficulty=0&judgeStatus=0&rp=0
# IN
select device_id ,gender, age, university, gpa
from user_profile
where university IN ("北京大学","复旦大学","山东大学");
# NOT IN
select device_id ,gender, age, university, gpa
from user_profile
where university NOT IN ("浙江大学");
count
# IN
select device_id ,gender, age, university, gpa
from user_profile
where university IN ("北京大学","复旦大学","山东大学");
# NOT IN
select device_id ,gender, age, university, gpa
from user_profile
where university NOT IN ("浙江大学");
count
https://www.nowcoder.com/practice/7d9a7b2d6b4241dbb5e5066d7549ca01?tpId=199&tags=&title=&difficulty=0&judgeStatus=0&rp=0
select count(gender) as male_num,avg(gpa)
from user_profile
where gender='male'
//avg并没有统计所有平均数
错误解决方案
1205 - Lock wait timeout exceeded; try restarting transaction
https://blog.csdn.net/u012248802/article/details/77866019?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522162926990516780269816425%2522%252C%2522scm%2522%253A%252220140713.130102334…%2522%257D&request_id=162926990516780269816425&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2allsobaiduend~default-1-77866019.first_rank_v2_pc_rank_v29&utm_term=1205±+Lock+wait+timeout+exceeded%3B+try+restarting+transaction&spm=1018.2226.3001.4187