18---sql 语句

 

1.       创建数据库

./usr/local/mysql/bin/mysql

Show databases;

Create database rx;

2.       创建表

Use rx;

Create yg.rx (employee_id int,name char(10), gender enum(‘M’,’W’), dept_id set (1,2,3,4), join_time date, salary int, phone int, address char(10), description char(10));

 ##查看创建表

Desc yg;

3.       向表中添加数据

Insert  into yg values(1,”xingxing”,’M’,’1’, ‘2010-12-16’, 2500,138350,’beijing’, ‘yg’);

4.       表中数据出错的修改方式

Update yg set employee_id=8 where name=’xingxing’;

##列属性的修改

Alter table yg modify address char(20);

5.       查询表中某个人的记录

Select * from yg where name=”xingxing”;

6.       按薪水查找大于3000的

Select name,salary>=3000 from yg;

Select * from yg where salary>=3000;

7.       每个部门有多少人

4个部门：

Select count(*) from yg group by dept_id;

每个部门；

Select count(*) from yg group by dept_id having dept_id=’2’;

8.       每个部门的平均工资

Select avg(salary) from yg group by dept_id;

Select avg(salary) from yg group by dept_id having dept_id=’1’;

9.       是否有人描述字符为空

##添加空字符的描述

Insert into yg values();

Insert into yg values(10,”niy”, ’M’, ’1’, ”2003-12-10”,1223,138,null,null);

Select * from yg where name is null;

10.   每个部门赚的最多的人

Select name,mix(salary) from yg group by debt_id;

Select name,mix(salary) from yg group by debt_id having debt_id=’1’;

11.   名字是以l 开头

Select name from yg where name like ”l%”;