本文主要是介绍SQL-DQL-数据查询语言，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
数据查询语言
select 字段列表
from 表名列表
where 条件列表
group by 分组字段列表
having 分组后条件列表
order by 排序字段列表
limit 分页参数1、基础查询
select 字段1[as 别名1],字段2[as 别名2]... from 表名
select * from 表名 # 全部字段
select distinct 字段列表 from 表名 # 去除重复记录insert into employee values(5,'67','人5','男',19,'123456789123456789','2019-09-10'),(6,'69','人6','女',19,'123456789123456789','2019-09-10'),(7,'61','人7','男',19,'123456789123456789','2019-09-10'),(8,'62','人8','男',19,'123456789123456789','2019-09-10'),(9,'64','人4','女',19,'123456789123456789','2019-09-10'),(10,'65','人4','男',19,'123456789123456789','2019-09-10'),(11,'66','人4','男',19,'123456789123456789','2019-09-10');
insert into employee values(12,'67','人5','女',19,'12345678912345678X','2019-09-10');
# 查询全部字段
select * from employee;
# 缺点：*不直观,影响开发效率
# 查询指定字段
select name,gender from employee;
# 查询字段取别名
select name as '姓名' from employee;
# 去重
select distinct name as'去重姓名' from employee;# 条件查询
select name from employee where gender = '女';
select name from employee where age >= 19;
select name from employee where idcard is null;
select name from employee where idcard is not null;
select name from employee where gender != '女';
select name from employee where age != 18;
select name from employee where age <> 18;
select name from employee where age>=15 && age<=20;
select name from employee where age>=15 and age<=20;
select name from employee where age between 15 and 20; #闭集
select name from employee where gender='女' and age<=20;
select name from employee where age=20 or age=19;
select name from employee where name in ('人1','人4');
select * from employee where id like '__'; # 模糊匹配,两个字符的id
select * from employee where idcard like '%X'; # 身份证号末尾为X
select * from employee where idcard like '_________________X'; # 17个下划线这篇关于SQL-DQL-数据查询语言的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
