常用的sql语句

【1】建立员工档案表
要求字段：员工员工编号，员工姓名，性别，工资，email，入职时间，部门。


【2】合理选择数据类型及字段修饰符，要求有NOT NULL，auto_increment, primary key等。

1. --  
2. -- make by kakane  
3. --  
4.   
5.   
6. DROP TABLE IF EXISTS `workers_info`;  
7. CREATE TABLE `workers_info` (  
8. int(11) NOT NULL AUTO_INCREMENT,  
9. varchar(20) NOT NULL,  
10.   `sex` enum(F,M,S),  
11. int(11) DEFAULT '0',  
12. varchar(30),  
13. date,  
14. varchar(30),  
15. PRIMARY KEY (`id`)  
16. ) ENGINE=MyISAM  DEFAULT CHARSET=utf8;  
17.   
18.   
19. mysql> alter table workers_info ADD sex  enum('F','M','S');

【3】查看表的结构

1. mysql> desc  workers_info;

【4】新增qq和tel字段，要求tel字段位于email前，要求入职时间是最后一个字段

  mysql> ALTER TABLE workers_info ADD tel varchar(15) after salary;

1. mysql> ALTER TABLE workers_info ADD qq int;  
2. ALTER TABLE workers_info MODIFY EmployedDates date after qq;

【5】把email字段修改成mailbox

 

mysql> ALTER TABLE workers_info CHANGE email mailbox varchar(30);

【6】向表里添加10条记录

  

mysql> INSERT INTO workers_info values(NULL,'xing',10000,'1598232123','[e-mail]','yanfa',736019646,20121221);

1. mysql> INSERT INTO workers_info (workername,salary,tel,mailbox,department,qq,EmployedDates) values('xing',10000,'1598232123','[e-mail]','yanfa',736019646,20121221);

 

【7】修改其中两条记录的tel和mailbox

  

mysql> UPDATE workers_info SET mailbox = '[e-mail]' WHERE id = 14;

1. mysql> UPDATE workers_info SET mailbox = '[e-mail]',tel='1246543423' WHERE id = 13;

【8】查看所添加记录

mysql> select * from workers_info;

【9】查看姓名和入职时间记录

 

mysql> select workername,EmployedDates from workers_info;

 

【10】查询入职时间在2003年以前的

1. mysql> select * from workers_info where year(EmployedDates) < 2003;

 

【11】查询工资最高和最低的员工姓名

1. mysql> select * from workers_info ORDER BY salary limit 1;  
2. mysql> select * from workers_info ORDER BY salary desc limit 1;

【12】查询平均工资

1. mysql> select avg(salary) from workers_info;

【13】统计男员工人数、女员工人数

1. mysql> select count(男) from workers_info where sex="M";  
2. mysql> select count(男) from workers_info where sex="M";

【14】按照入职时间先后进行排序，并显示前5位员工姓名

1. mysql> select * from workers_info ORDER BY EmployedDates limit 5;