西安网站北京营销公司比较好的

本篇是基于上篇mysql基本查询的一些OJ题

MySQL基本查询传送门：【MySQL篇】MySQL基本查询详解-CSDN博客

批量插入数据_牛客题霸_牛客网

insert语句 

insert into actor values (1,'PENELOPE','GUINESS','2006-02-15 12:34:33');
insert into actor values (2,'NICK','WAHLBERG','2006-02-15 12:34:33');

 找出所有员工当前薪水salary情况_牛客题霸_牛客网

distinct去重+order by 排序 

select distinct salary from salaries order by salary desc;

 查找最晚入职员工的所有信息_牛客题霸_牛客网

select * from employees order by hire_date desc limit 1;

 查找入职员工时间升序排名的情况下的倒数第三的员工所有信息_牛客题霸_牛客网

select * from employees where hire_date=(select distinct hire_date from employees 
order by hire_date desc limit 1 offset 2);

 查找薪水记录超过15条的员工号emp_no以及其对应的记录次_牛客题霸_牛客网

group by子句及聚合函数 

select emp_no,count(emp_no) as t from salaries group by emp_no having t>15;

 182. 查找重复的电子邮箱 - 力扣（LeetCode）

group by子句+聚合函数 

select Email from Person group by Email having count(Email)>1;

595. 大的国家 - 力扣（LeetCode）

where子句 

select name,population,area from World where area>=3000000 or population>=25000000;