数据库查询练习

数据库查询练习

1.建表
mysql> create table worker(
department_id int(11) not null comment ‘部门号’,
worker_id int(11) primary key not null comment ‘职工号’,
worker_date date not null comment ‘工作时间’,
wages float(8,2) not null comment ‘工资’,
politics varchar(10) not null default ‘群众’ comment ‘政治面貌’,
name varchar(20) not null comment ‘姓名’,
borth_date date not null comment ‘出生日期’ );

2.插入数据
mysql> insert into worker values (101,1001,‘2015-5-4’,3500.00,‘群众’,‘张三’,‘1990-7-1’);

mysql> insert into worker values (101,1002,‘2017-2-6’,3200.00,‘团员’,‘李四’,‘1997-2–8’);

mysql> insert into worker values (102,1003,‘2011-1-4’,8500.00,‘党员’,‘王亮’,‘1983-6-8’);

mysql> insert into worker values (102,1004,‘2016-10-10’,5500.00,‘群众’,‘赵六’,‘1994-9-5’);

mysql> insert into worker values (102,1005,‘2014-4-1’,4800.00,‘党员’,‘钱七’,‘1992-12-30’);

mysql> insert into worker values (102,1006,‘2017-5-5’,4500.00,‘党员’,‘孙八’,‘1996-12-2’);

3.完成查询

(1)、显示所有职工的基本信息。
mysql> select * from worker;

(2)、查询所有职工所属部门的部门号，不显示重复的部门号。
mysql> select distinct department_id from worker;

(3)、求出所有职工的人数。  
mysql> select count(worker_id) from worker;

(4)、列出最高工和最低工资。
mysql> select max(wages),min(wages) from worker;

(5)、列出职工的平均工资和总工资。   
mysql> select avg(wages),sum(wages) from worker;

(6)、创建一个只有职工号、姓名和参加工作的新表，名为工作日期表workdate（数据来源于worker表）
mysql> create table workdate select worker_id,department_id,name from worker;

(7)、显示所有党员的年龄。 
mysql> select name,politics,timestampdiff(year,borth_date,curdate()) as "年龄" from worker where politics='党员';

(8)、列出工资在2000－5000之间的所有职工姓名。
mysql> select * from worker where wages>=2000 and wages<=5000;

(9)、列出所有孙姓和李姓的职工姓名。
mysql> select name from worker where name like "李%" or name like "孙%";

(10)、列出所有部门号为2和3且不是党员的职工号、姓名。  
mysql> select worker_id,name from worker where  not department_id like "%1" and not politics like "党员";

(11)、将职工表worker中的职工按出生的先后顺序排序。
mysql> select * from worker order by borth_date asc;

(12)、显示工资最高的前3名职工的职工号和姓名。 
mysql> select worker_id,name from worker order by wages desc limit 3;

(13)、求出各部门党员的人数。 
mysql> select department_id,count(politics) from worker where politics like "党员" group by department_id;

(14)、统计各部门的工资和平均工资
mysql> select department_id,sum(wages),avg(wages) from worker group by department_id;

(15)、列出总人数大于等于4的部门号和总人数。
mysql> select department_id,count(worker_id) from worker group by department_id having count(worker_id)>=4;