MySQL

这是一篇关于MySQL的思维导图，其内容包含SELECT语句，where从句以及利用grouo by函数进行分组等知识点

MySQL

• SELECT语句
  • select * from 表名 select--选择语句 *--查询表中所有数据
  • 筛选核心维度:select 字段名 from 表名; select month,year from sales;
• where语句
  • 多条件筛选并列：where 条件1 and 条件2 select *from sales where year=2019 and month=2;
  • 多条件筛选(或者)：where 条件1 or 条件2 select *from sales where year=2019 and year=2020;
  • 范围筛选(非连续)：where ... in ... select *from sales where year in(2019,2020);
  • 范围筛选(连续)：where ... between ... select *from sales where month between 1 and 7;
  • 语句集合！一次查清问题所需数据 select*from sales where year in (2019,2020)and (month between 1and 7);
• 利用sum（） 函数查询销售额 select sum(price) from sales where year in (2019,2020)and (month between 1and 7);
• 利用group by函数进行分组 select sum(price) from sales where year in (2019,2020)and(month between 1 and 7) group by year；
• 利用order by函数进行分组 select sum(price) from sales where year in (2019,2020)and(month between 1 and 7) group by year order by year；
• 综合运用select where group by语句进行业务分析
  • select year，sum(price) from sales where year in (2019,2020)and (month between 1 and 7) group by year;
  • 按年份降序 加一个desc