【Oracle学习笔记-5--】集合操作之union，intersect和minus操作
时间：2015-07-08 10:52:53
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--union并操作
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘C%‘
union
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘S%‘;
--等价于
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘C%‘or e.last_name like ‘S%‘;
-- intersect交集操作
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘C%‘or e.last_name like ‘S%‘
intersect
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘S%‘or e.last_name like ‘T%‘;
--等价于
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘S%‘;
--minus差操作
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘C%‘or e.last_name like ‘S%‘
minus
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘S%‘or e.last_name like ‘T%‘;
--等价于
select e.employee_id,e.last_name from hr.employees e
where e.last_name like ‘C%‘;
博客：
淘宝-代做毕设：
原文：http://www.cnblogs.com/ssslinppp/p/4629412.html
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