mysql的基本语法及相应的练习,标对号的是没问题的,只有求交集和差集的时候执行不了,可能是mysql不支持intersect和minus ,背景黄色部分是进阶阶段-The basic syntax of mysql and the corresponding practice standard checkmark is no problem, only seeking the intersection and difference set when the execution can not,

查询练习（45道题） 题目：设有一数据库，包括四个表：学生表（Student）、课程表（Course）、成绩表（Score）以及教师信息表（Teacher）。(Topic: there is a database, including four tables: student table (Student), curriculum schedule (Course), achievement table (Score), and teacher information table)

数据库练习， 学的越好提高的越多， 数据库中的练习可以改进得更好。(The exercises in the database can be improved better. The better the learning is, the more)