(四)查询结果限制返回行数
4、查询结果限制返回行数
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题目:现在运营只需要查看前2个用户明细设备ID数据,请你从用户信息表 user_profile 中取出相应结果。
示例:
id
device_id
gender
age
university
province
1
2138
male
21
北京大学
Beijing
2
3214
male
复旦大学
Shanghai
3
6543
female
20
北京大学
Beijing
4
2315
female
23
浙江大学
ZheJiang
5
5432
male
25
山东大学
Shandong
根据输入,你的查询应返回以下结果:
device_id
2138
3214 示例1
输入: drop table if exists user_profile; CREATE TABLE `user_profile` ( `id` int NOT NULL, `device_id` int NOT NULL, `gender` varchar(14) NOT NULL, `age` int , `university` varchar(32) NOT NULL, `province` varchar(32) NOT NULL); INSERT INTO user_profile VALUES(1,2138,"male",21,"北京大学","BeiJing"); INSERT INTO user_profile VALUES(2,3214,"male",null,"复旦大学","Shanghai"); INSERT INTO user_profile VALUES(3,6543,"female",20,"北京大学","BeiJing"); INSERT INTO user_profile VALUES(4,2315,"female",23,"浙江大学","ZheJiang"); INSERT INTO user_profile VALUES(5,5432,"male",25,"山东大学","Shandong");
输出: 2138 3214
答案:
select device_id from user_profile limit 0,2
执行结果: