[{"createTime":1735734952000,"id":1,"img":"hwy_ms_500_252.jpeg","link":"https://activity.huaweicloud.com/cps.html?fromacct=261f35b6-af54-4511-a2ca-910fa15905d1&utm_source=V1g3MDY4NTY=&utm_medium=cps&utm_campaign=201905","name":"华为云秒杀","status":9,"txt":"华为云38元秒杀","type":1,"updateTime":1735747411000,"userId":3},{"createTime":1736173885000,"id":2,"img":"txy_480_300.png","link":"https://cloud.tencent.com/act/cps/redirect?redirect=1077&cps_key=edb15096bfff75effaaa8c8bb66138bd&from=console","name":"腾讯云秒杀","status":9,"txt":"腾讯云限量秒杀","type":1,"updateTime":1736173885000,"userId":3},{"createTime":1736177492000,"id":3,"img":"aly_251_140.png","link":"https://www.aliyun.com/minisite/goods?userCode=pwp8kmv3","memo":"","name":"阿里云","status":9,"txt":"阿里云2折起","type":1,"updateTime":1736177492000,"userId":3},{"createTime":1735660800000,"id":4,"img":"vultr_560_300.png","link":"https://www.vultr.com/?ref=9603742-8H","name":"Vultr","status":9,"txt":"Vultr送$100","type":1,"updateTime":1735660800000,"userId":3},{"createTime":1735660800000,"id":5,"img":"jdy_663_320.jpg","link":"https://3.cn/2ay1-e5t","name":"京东云","status":9,"txt":"京东云特惠专区","type":1,"updateTime":1735660800000,"userId":3},{"createTime":1735660800000,"id":6,"img":"new_ads.png","link":"https://www.iodraw.com/ads","name":"发布广告","status":9,"txt":"发布广告","type":1,"updateTime":1735660800000,"userId":3},{"createTime":1735660800000,"id":7,"img":"yun_910_50.png","link":"https://activity.huaweicloud.com/discount_area_v5/index.html?fromacct=261f35b6-af54-4511-a2ca-910fa15905d1&utm_source=aXhpYW95YW5nOA===&utm_medium=cps&utm_campaign=201905","name":"底部","status":9,"txt":"高性能云服务器2折起","type":2,"updateTime":1735660800000,"userId":3}]
<>1、把查询结果去除重复记录【distinct】
注意：原表数据不会被修改，只是查询结果去重。 去重需要使用一个关键字：distinct mysql> select distinct job from
emp; +-----------+ | job | +-----------+ | CLERK | | SALESMAN | | MANAGER | |
ANALYST | | PRESIDENT | +-----------+ // 这样编写是错误的，语法错误。 //
distinct只能出现在所有字段的最前方。 mysql> select ename,distinct job from emp; //
distinct出现在job,deptno两个字段之前，表示两个字段联合起来去重。 mysql> select distinct job,deptno
from emp; +-----------+--------+ | job | deptno | +-----------+--------+ |
CLERK | 20 | | SALESMAN | 30 | | MANAGER | 20 | | MANAGER | 30 | | MANAGER | 10
| | ANALYST | 20 | | PRESIDENT | 10 | | CLERK | 30 | | CLERK | 10 |
+-----------+--------+ 统计一下工作岗位的数量？ select count(distinct job) from emp;
+---------------------+ | count(distinct job) | +---------------------+ | 5 |
+---------------------+
