SQL学习笔记八 索引，表连接，子查询，ROW_NUMBER

索引

经常要查询的语句，则给它建一个索引

表连接

select t_oders as o join t_customers as c on o.customerid = c.id

子查询

单值子查询

单列多值子查询

row_number()函数

row_number() over(order by fsalary desc)