sql面试01

select * from employees;和select * from employees where commission_pct like '%%'  and last_name like '%%';结果是否一样？？？

不一定   如果考虑字段有空就不一样

如果select * from employees where commission_pct like '%%'  and last_name like '%%';里面and改为or呢？？？  

结果是一样的