mysql 常用语句 -转

http://blog.csdn.net/kakane/article/details/7401111

【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。

 

    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

ALTER TABLE workers_info CHANGE email mailbox varchar(30);

 【6】向表里添加10条记录

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]',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(女) from workers_info where sex="W"; 

 【14】把email字段长度修改为255

mysql> ALTER TABLE workers_info MODIFY COLUMN email varchar(255);

【15】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;