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);