SQL 语法基础

https://pdai.tech/md/db/sql-lan/sql-lan.html

SQL 语句练习

https://pdai.tech/md/db/sql-lan/sql-lan-pratice.html

SQL 题目进阶

https://pdai.tech/md/db/sql-lan/sql-lan-leetcode.html

SQL 语句优化

负向查询不能使用索引

select name from user where id not in (1,3,4);

修改为

select name from user where id in (2,5,6);