【mysql】mysql 常用建表语句

【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。

--
-- make by kakane
--


DROP TABLE IF EXISTS `workers_info`;
CREATE TABLE `workers_info` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `workername` varchar(20) NOT NULL,
  `sex` enum(F,M,S),
  `salary` int(11) DEFAULT '0',
  `email`  varchar(30),
  `EmployedDates`  date,
  `department`  varchar(30),
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8;


mysql> alter table workers_info ADD sex  enum('F','M','S');

【3】查看表的结构

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;

mysql> ALTER TABLE workers_info ADD qq int;
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','xing@qq.com','yanfa',736019646,20121221);

mysql> INSERT INTO workers_info (workername,salary,tel,mailbox,department,qq,EmployedDates) values('xing',10000,'1598232123','xing@qq.com','yanfa',736019646,20121221);

 
【7】修改其中两条记录的tel和mailbox
  mysql> UPDATE workers_info SET mailbox = 'haha@qq.com' WHERE id = 14;

mysql> UPDATE workers_info SET mailbox = 'haha@qq.com',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

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

【11】查询工资最高和最低的员工姓名

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

【12】查询平均工资

mysql> select avg(salary) from workers_info;

【13】统计男员工人数、女员工人数

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

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