SQL inner join的问题

Question

假设数据库表结构如 这里所示

select employees.employees.emp_no, 
    employees.employees.first_name, 
    employees.employees.last_name, 
    employees.salaries.salary
from employees.employees
inner join employees.salaries
on employees.employees.emp_no = employees.salaries.emp_no
limit 500

和

select employees.employees.emp_no, 
    employees.employees.first_name, 
    employees.employees.last_name, 
    employees.salaries.salary
from employees.employees,employees.salaries
where employees.employees.emp_no = employees.salaries.emp_no
limit 500

有哪些区别？

Answer 1

请优先使用搜索引擎，INNER JOIN ON vs WHERE clause，大意就是它们是等价的，but inner join is more readable, and easier to modify.

Answer 2

使用inner join 跟 where作联结是一样的，inner join在多表联结和联结条件复杂的情况下可读性要好很多，语义也更强，尤其是同时还有left join的情况下。推荐使用 inner join