Mysql查询语句（select）相关练习_mysq查询练习-优快云博客

本文链接：https://blog.youkuaiyun.com/Crrrrrr9/article/details/145187098

一.练习目标

二.实现目标

1.建库建表

mysql> create database mydb8_worker;
Query OK, 1 row affected (0.00 sec)-------建立数据库mydb8_worker





mysql>create table t_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');
Query OK, 0 rows affected, 3 warnings (0.01 sec)-------创建表格t_worker

2.插入数据

mysql> insert into t_worker value(
    -> 101,1001,'2015-5-4',7500.00,'群众','张春燕','1990-7-1');
Query OK, 1 row affected (0.00 sec)

mysql> insert into t_worker value(
    -> 101,1002,'2019-2-6',5200.00,'团员','李名博','1997-2-8');
Query OK, 1 row affected (0.00 sec)

mysql> insert into t_worker value(
    -> 102,1003,'2008-1-4',10500.00,'党员','王博涵','1983-6-8');
Query OK, 1 row affected (0.00 sec)

mysql> insert into t_worker value(
    -> 102,1004,'2016-10-10',5500.00,'群众','赵小军','1994-9-5');
Query OK, 1 row affected (0.00 sec)

mysql> insert into t_worker value(
    -> 102,1005,'2014-4-1' , 8800.00,'党员','钱有财','1992-12-30');
Query OK, 1 row affected (0.00 sec)

mysql> insert into t_worker value(
    -> 103,1006,'2019-5-5',5500.00,'党员','孙菲菲','1996-9-2');
Query OK, 1 row affected (0.00 sec)
                            以上为按练习要求插入的所有数据

3.完成查询

(1)显示所有职工的基本信息

mysql> select * from t_worker;
+---------------+-----------+-------------+----------+----------+--------+------------+
| department_id | worker_id | worker_date | wages    | politics | name   | borth_date |
+---------------+-----------+-------------+----------+----------+--------+------------+
|           101 |      1001 | 2015-05-04  |  7500.00 | 群众     | 张春燕 | 1990-07-01 |
|           101 |      1002 | 2019-02-06  |  5200.00 | 团员     | 李名博 | 1997-02-08 |
|           102 |      1003 | 2008-01-04  | 10500.00 | 党员     | 王博涵 | 1983-06-08 |
|           102 |      1004 | 2016-10-10  |  5500.00 | 群众     | 赵小军 | 1994-09-05 |
|           102 |      1005 | 2014-04-01  |  8800.00 | 党员     | 钱有财 | 1992-12-30 |
|           103 |      1006 | 2019-05-05  |  5500.00 | 党员     | 孙菲菲 | 1996-09-02 |
+---------------+-----------+-------------+----------+----------+--------+------------+
6 rows in set (0.00 sec)

(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 t_worker;
+---------------+
| department_id |
+---------------+
|           101 |
|           102 |
|           103 |
+---------------+
3 rows in set (0.00 sec)

(3)求出所有职工的人数

mysql> select count(worker_id) '职工人数' from t_worker;
+----------+
| 职工人数 |
+----------+
|        6 |
+----------+
1 row in set (0.00 sec)

(4)列出最高工和最低工资

mysql> select max(wages) '最高工资',min(wages) '最低工资' from t_worker;
+----------+----------+
| 最高工资 | 最低工资 |
+----------+----------+
| 10500.00 |  5200.00 |
+----------+----------+
1 row in set (0.00 sec)

(5)列出职工的平均工资和总工资

mysql> select round(avg(wages),2) '平均工资',round( sum(wages))'总工资' from t_worker;
+----------+--------+
| 平均工资 | 总工资 |
+----------+--------+
|  7166.67 |  43000 |
+----------+--------+
1 row in set (0.00 sec)

(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

mysql> create table t_workdate select worker_id ,name ,worker_date from t_worker;
Query OK, 6 rows affected (0.01 sec)
Records: 6  Duplicates: 0  Warnings: 0

查询建表内容信息：

mysql> select * from t_workdate;
+-----------+--------+-------------+
| worker_id | name   | worker_date |
+-----------+--------+-------------+
|      1001 | 张春燕 | 2015-05-04  |
|      1002 | 李名博 | 2019-02-06  |
|      1003 | 王博涵 | 2008-01-04  |
|      1004 | 赵小军 | 2016-10-10  |
|      1005 | 钱有财 | 2014-04-01  |
|      1006 | 孙菲菲 | 2019-05-05  |
+-----------+--------+-------------+
6 rows in set (0.00 sec)

(7)显示所有党员的年龄

mysql> select year(now())-year(borth_date) '年龄' from t_worker where politics='党员';
+------+
| 年龄 |
+------+
|   42 |
|   33 |
|   29 |
+------+
3 rows in set (0.00 sec)

(8)列出工资在4000-8000之间的所有职工姓名

mysql> select name from t_worker where wages>=4000 and wages<=8000;
+--------+
| name   |
+--------+
| 张春燕 |
| 李名博 |
| 赵小军 |
| 孙菲菲 |
+--------+
4 rows in set (0.00 sec)

(9)列出所有孙姓和李姓的职工姓名

mysql> select name from t_worker where name like '孙%' or name like '李%';
+--------+
| name   |
+--------+
| 李名博 |
| 孙菲菲 |
+--------+
2 rows in set (0.00 sec)

(10)列出所有部门号为102和103日不是党员的职工号、姓名

mysql> select worker_id ,name from t_worker where (department_id<=>102 or department_id<=>103) and politics!='党员';
+-----------+--------+
| worker_id | name   |
+-----------+--------+
|      1004 | 赵小军 |
+-----------+--------+
1 row in set (0.00 sec)

(11)将职工表t worker中的职工按出生的先后顺序排序

mysql> select * from t_worker order by  borth_date;
+---------------+-----------+-------------+----------+----------+--------+------------+
| department_id | worker_id | worker_date | wages    | politics | name   | borth_date |
+---------------+-----------+-------------+----------+----------+--------+------------+
|           102 |      1003 | 2008-01-04  | 10500.00 | 党员     | 王博涵 | 1983-06-08 |
|           101 |      1001 | 2015-05-04  |  7500.00 | 群众     | 张春燕 | 1990-07-01 |
|           102 |      1005 | 2014-04-01  |  8800.00 | 党员     | 钱有财 | 1992-12-30 |
|           102 |      1004 | 2016-10-10  |  5500.00 | 群众     | 赵小军 | 1994-09-05 |
|           103 |      1006 | 2019-05-05  |  5500.00 | 党员     | 孙菲菲 | 1996-09-02 |
|           101 |      1002 | 2019-02-06  |  5200.00 | 团员     | 李名博 | 1997-02-08 |
+---------------+-----------+-------------+----------+----------+--------+------------+
6 rows in set (0.00 sec)

(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 t_worker order by wages desc limit 3;
+-----------+--------+
| worker_id | name   |
+-----------+--------+
|      1003 | 王博涵 |
|      1005 | 钱有财 |
|      1001 | 张春燕 |
+-----------+--------+
3 rows in set (0.00 sec)

(13)求出各部门党员的人数

mysql> select department_id,'部门号',count(worker_id) '党员人数' from t_worker where
    -> politics='党员' group by department_id;
+---------------+--------+----------+
| department_id | 部门号 | 党员人数 |
+---------------+--------+----------+
|           102 | 部门号 |        2 |
|           103 | 部门号 |        1 |
+---------------+--------+----------+
2 rows in set (0.00 sec)

(14)统计各部门的工资和平均工资并保留2位小数

mysql> select department_id,'部门号',sum(wages) '部门工资总和', round(avg(wages),2) '部门平均工资' from t_worker group by department_id;
+---------------+--------+--------------+--------------+
| department_id | 部门号 | 部门工资总和 | 部门平均工资 |
+---------------+--------+--------------+--------------+
|           101 | 部门号 |     12700.00 |         6350 |
|           102 | 部门号 |     24800.00 |      8266.67 |
|           103 | 部门号 |      5500.00 |         5500 |
+---------------+--------+--------------+--------------+
3 rows in set (0.00 sec)

(15）列出总人数大于等于3的部门号和总人数

mysql> select department_id '部门号', count(worker_id) '人数' from t_worker group by department_id having count(worker_id)>=3;
+--------+------+
| 部门号 | 人数 |
+--------+------+
|    102 |    3 |
+--------+------+
1 row in set (0.00 sec)

三.练习总结

本次练习旨在练习数据库查询（select）指令的基本查询，条件查询，聚合函数，分组查询，排序查询，分页查询。总结语法如下：

select 字段列表 from 表名列表 where 条件列表 group by 分组字段列表 having 分组后条
件列表 order by 排序字段列表 limit 分页参数