mysql表查询

mysql表查询
15 赵清野
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
| employee_id | name | gender | dept_id | salary | phone       | address | description | join_time  |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
|           2 | xh   | F      | CW      | 3252.8 | 12345678901 | beijing | good        | 2012-12-26 |
|           1 | xm   | M      | CW      | 3552.8 | 12345678901 | beijing | good        | 2012-12-26 |
|           3 | xg   | M      | CW      | 4252.3 | 12345678901 | beijing | good        | 2012-12-24 |
|           4 | xy   | F      | CW      | 3472.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           5 | lm   | M      | KF      | 2472.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           6 | wa   | F      | KF      | 5472.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           7 | hg   | M      | KF      | 3122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           8 | fg   | F      | KF      | 7122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           9 | ll   | M      | SC      | 4122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          10 | lt   | F      | SC      | 6522.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          11 | lr   | M      | SC      | 7122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          12 | zr   | F      | SC      | 4422.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          13 | zh   | M      | RS      | 2422.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          14 | ch   | F      | RS      | 2522.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          15 | xh   | F      | RS      | 3122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          16 | sc   | M      | RS      | 3022.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          17 | jk   | M      | RS      | 4022.2 | 12345678901 | beijing | NULL        | 2012-12-24 |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
查找为姓名为ch
mysql> select * from work.a where name='ch';
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
| employee_id | name | gender | dept_id | salary | phone       | address | description | join_time  |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
|          14 | ch   | F      | RS      | 2522.2 | 12345678901 | beijing | good        | 2012-12-24 |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
1 row in set (0.00 sec)

 

描述为空
mysql> insert into work.a values (17,'jk','M','RS',4022.2,12345678901,'beijing','NULL','2012-12-24');
Query OK, 1 row affected (0.00 sec)

          17 | jk   | M      | RS      | 4022.2 | 12345678901 | beijing | NULL        | 2012-12-24 |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+

工资大于3000的人员
mysql> select * from work.a where salary>3000;
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
| employee_id | name | gender | dept_id | salary | phone       | address | description | join_time  |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
|           2 | xh   | F      | CW      | 3252.8 | 12345678901 | beijing | good        | 2012-12-26 |
|           1 | xm   | M      | CW      | 3552.8 | 12345678901 | beijing | good        | 2012-12-26 |
|           3 | xg   | M      | CW      | 4252.3 | 12345678901 | beijing | good        | 2012-12-24 |
|           4 | xy   | F      | CW      | 3472.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           6 | wa   | F      | KF      | 5472.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           7 | hg   | M      | KF      | 3122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           8 | fg   | F      | KF      | 7122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           9 | ll   | M      | SC      | 4122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          10 | lt   | F      | SC      | 6522.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          11 | lr   | M      | SC      | 7122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          12 | zr   | F      | SC      | 4422.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          15 | xh   | F      | RS      | 3122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          16 | sc   | M      | RS      | 3022.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          17 | jk   | M      | RS      | 4022.2 | 12345678901 | beijing | NULL        | 2012-12-24 |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+

每个部门人数
mysql> select dept_id,count(*) from work.a group by dept_id;
+---------+----------+
| dept_id | count(*) |
+---------+----------+
| CW      |        4 |
| KF      |        4 |
| SC      |        4 |
| RS      |        5 |
+---------+----------+
4 rows in set (0.00 sec)

每个部门平均工资
mysql> select dept_id,avg(salary) from work.a group by dept_id;
+---------+-----------------+
| dept_id | avg(salary)     |
+---------+-----------------+
| CW      | 3632.5249633789 |
| KF      | 4547.2000732422 |
| SC      | 5547.2001953125 |
| RS      | 3022.1999511719 |
+---------+-----------------+
4 rows in set (0.00 sec)

名字已l为开头
mysql>  select * from work.a where name like 'l%';
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
| employee_id | name | gender | dept_id | salary | phone       | address | description | join_time  |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
|           5 | lm   | M      | KF      | 2472.2 | 12345678901 | beijing | good        | 2012-12-24 |
|           9 | ll   | M      | SC      | 4122.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          10 | lt   | F      | SC      | 6522.2 | 12345678901 | beijing | good        | 2012-12-24 |
|          11 | lr   | M      | SC      | 7122.2 | 12345678901 | beijing | good        | 2012-12-24 |
+-------------+------+--------+---------+--------+-------------+---------+-------------+------------+
 
每个部门女员工工资最高的
mysql> select dept_id, max(salary) from md.a where gender= 'F' group by dept_id;
+---------+-------------+
| dept_id | max(salary) |
+---------+-------------+
| KF      |        2500 |
| RS      |        6000 |
| CW      |        4500 |
+---------+-------------+