distinct

标签：

1:select distinct department_id from employees;

2:select distinct department_id from employees where department_id is not null;

3:select distinct department_id from employees

where department_id not in(100);

4:select distinct department_id from employees

where department_id is not null and department_id not in(100);

distinct

标签：

原文地址：http://www.cnblogs.com/material/p/5865424.html