MySQL 查询常用操作——排序 order by

Posted 2023-04-07 酸菜鱼土豆大侠

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mysql中常用的查询操作，首先是能直接从表中直接取出数据，接着能对查询结果做一些简单的处理，比如去重等，然后是根据条件查询数据，包括精准查询、模糊查询以及按照数据的某个范围或者指定多个指标进行查询，值得注意的是，MySQL中的一些查询会忽略空值。最后是将查询结果进行排序，主要包括升序和降序以及多个字段的先后排序处理。

第三部分主要介绍order by 语句——对查询结果进行排序。

一、具体方法

对查询结果排序

1、表达式后面可选地跟着 asc 或 desc 来指示排序方向。如果没有指定方向，默认为 asc。
2、升序时先对空值排序，降序时最后对空值排序。

问题	类型	方法
按照用户年龄进行升序排列	升序	order by a
先按照age升序，再按照gpa升序	多列排序	order by a,b
先按照age降序，再按照gpa降序	多列降序	order by a desc, b desc

扩展：

高级用法前往：MySQL union 和 order by 一起使用需要注意的问题

二、实例

已知有用户信息表user_profile（device_id 设备ID, gender 性别, age 年龄, university 学校, gpa）

id	device_id	gender	age	university	gpa
1	2138	male	21	北京大学	3.4
2	3214	male		复旦大学	4.0
3	6543	female	20	北京大学	3.2
4	2315	female	23	浙江大学	3.6
5	5432	male	25	山东大学	3.8
6	2131	male	28	北京师范大学	3.3

题目1：取出用户的device_id、age、university信息，并按照用户年龄进行升序排列

【分类】：升序

【知识点】：order by a

求解代码

select 
	device_id,
	age,
  university
from user_profile
order by age;

结果

device_id	age	university
3214	None	复旦大学
6543	20	北京大学
2138	21	北京大学
2315	23	浙江大学
5432	25	山东大学
2131	28	北京师范大学

题目2：取出用户信息表中的device_id,gpa,age数据，并先按照gpa升序排序，再按照age升序排序输出

【分类】：多列升序

【知识点】：order by a ,b

求解代码

select
    device_id,
    age,
    gpa
from user_profile
order by age,gpa;

结果

device_id	age	gpa
3214	None	4.0
6543	20	3.2
2138	21	3.4
2315	23	3.6
5432	25	3.8
2131	28	3.3

题目3：取出用户信息表中的device_id,gpa,age数据，并先按照gpa、年龄降序排序输出

【分类】：多列降序

【知识点】： order by a desc, b desc

求解代码

select
    device_id,
    age,
    gpa
from user_profile
order by age desc,gpa desc;

结果

device_id	age	gpa
2131	28	3.3
5432	25	3.8
2315	23	3.6
2138	21	3.4
6543	20	3.2
3214	None	4.0

创建 user_profile 表的代码

-- ----------------------------
-- Table structure for user_profile
-- ----------------------------
DROP TABLE IF EXISTS `user_profile`;
CREATE TABLE `user_profile`  (
  `id` int(11) NOT NULL,
  `device_id` int(11) NOT NULL,
  `gender` varchar(14) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `age` int(11) NULL DEFAULT NULL,
  `university` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `gpa` float NULL DEFAULT NULL
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of user_profile
-- ----------------------------
INSERT INTO `user_profile` VALUES (1, 2138, 'male', 21, '北京大学', 3.4);
INSERT INTO `user_profile` VALUES (2, 3214, 'male', NULL, '复旦大学', 4);
INSERT INTO `user_profile` VALUES (3, 6543, 'female', 20, '北京大学', 3.2);
INSERT INTO `user_profile` VALUES (4, 2315, 'female', 23, '浙江大学', 3.6);
INSERT INTO `user_profile` VALUES (5, 5432, 'male', 25, '山东大学', 3.8);
INSERT INTO `user_profile` VALUES (6, 2131, 'male', 28, '北京师范大学', 3.3);

SET FOREIGN_KEY_CHECKS = 1;

mysql 数据操作单表查询查询排序: order by

如果不指定排序默认是按照id字段从小到大排序的升序

mysql> select * from employee;
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| id | name       | sex    | age | hire_date  | post      | post_comment | salary     | office | depart_id |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
|  1 | alex       | male   |  78 | 2015-03-02 | teacher   | NULL         | 1000000.31 |    401 |         1 |
|  2 | yuanhao    | male   |  73 | 2014-07-01 | teacher   | NULL         |    3500.00 |    401 |         1 |
|  3 | liwenzhou  | male   |  28 | 2012-11-01 | teacher   | NULL         |    2100.00 |    401 |         1 |
|  4 | jingliyang | female |  18 | 2011-02-11 | teacher   | NULL         |    9000.00 |    401 |         1 |
|  5 | jinxin     | male   |  18 | 1900-03-01 | teacher   | NULL         |   30000.00 |    401 |         1 |
|  6 | 成龙       | male   |  48 | 2010-11-11 | teacher   | NULL         |   10000.00 |    401 |         1 |
|  7 | 歪歪       | female |  48 | 2015-03-11 | sale      | NULL         |    3000.13 |    402 |         2 |
|  8 | 丫丫       | female |  38 | 2010-11-01 | sale      | NULL         |    2000.35 |    402 |         2 |
|  9 | 丁丁       | female |  18 | 2011-03-12 | sale      | NULL         |    1000.37 |    402 |         2 |
| 10 | 星星       | female |  18 | 2016-05-13 | sale      | NULL         |    3000.29 |    402 |         2 |
| 11 | 格格       | female |  28 | 2017-01-27 | sale      | NULL         |    4000.33 |    402 |         2 |
| 12 | 张野       | male   |  28 | 2016-03-11 | operation | NULL         |   10000.13 |    403 |         3 |
| 13 | 程咬金     | male   |  18 | 1997-03-12 | operation | NULL         |   20000.00 |    403 |         3 |
| 14 | 程咬银     | female |  18 | 2013-03-11 | operation | NULL         |   19000.00 |    403 |         3 |
| 15 | 程咬铜     | male   |  18 | 2015-04-11 | operation | NULL         |   18000.00 |    403 |         3 |
| 16 | 程咬铁     | female |  18 | 2014-05-12 | operation | NULL         |   17000.00 |    403 |         3 |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
16 rows in set (0.10 sec)

order by 不指定 asc 默认就是升序

需求按照年龄从小到大排序升序

asc 是升序

mysql> select * from employee order by age asc;
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| id | name       | sex    | age | hire_date  | post      | post_comment | salary     | office | depart_id |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| 16 | 程咬铁     | female |  18 | 2014-05-12 | operation | NULL         |   17000.00 |    403 |         3 |
| 15 | 程咬铜     | male   |  18 | 2015-04-11 | operation | NULL         |   18000.00 |    403 |         3 |
| 14 | 程咬银     | female |  18 | 2013-03-11 | operation | NULL         |   19000.00 |    403 |         3 |
| 13 | 程咬金     | male   |  18 | 1997-03-12 | operation | NULL         |   20000.00 |    403 |         3 |
| 10 | 星星       | female |  18 | 2016-05-13 | sale      | NULL         |    3000.29 |    402 |         2 |
|  9 | 丁丁       | female |  18 | 2011-03-12 | sale      | NULL         |    1000.37 |    402 |         2 |
|  5 | jinxin     | male   |  18 | 1900-03-01 | teacher   | NULL         |   30000.00 |    401 |         1 |
|  4 | jingliyang | female |  18 | 2011-02-11 | teacher   | NULL         |    9000.00 |    401 |         1 |
| 12 | 张野       | male   |  28 | 2016-03-11 | operation | NULL         |   10000.13 |    403 |         3 |
|  3 | liwenzhou  | male   |  28 | 2012-11-01 | teacher   | NULL         |    2100.00 |    401 |         1 |
| 11 | 格格       | female |  28 | 2017-01-27 | sale      | NULL         |    4000.33 |    402 |         2 |
|  8 | 丫丫       | female |  38 | 2010-11-01 | sale      | NULL         |    2000.35 |    402 |         2 |
|  7 | 歪歪       | female |  48 | 2015-03-11 | sale      | NULL         |    3000.13 |    402 |         2 |
|  6 | 成龙       | male   |  48 | 2010-11-11 | teacher   | NULL         |   10000.00 |    401 |         1 |
|  2 | yuanhao    | male   |  73 | 2014-07-01 | teacher   | NULL         |    3500.00 |    401 |         1 |
|  1 | alex       | male   |  78 | 2015-03-02 | teacher   | NULL         | 1000000.31 |    401 |         1 |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
16 rows in set (0.00 sec)

不加asc

mysql> select * from employee order by age ;
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| id | name       | sex    | age | hire_date  | post      | post_comment | salary     | office | depart_id |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| 16 | 程咬铁     | female |  18 | 2014-05-12 | operation | NULL         |   17000.00 |    403 |         3 |
| 15 | 程咬铜     | male   |  18 | 2015-04-11 | operation | NULL         |   18000.00 |    403 |         3 |
| 14 | 程咬银     | female |  18 | 2013-03-11 | operation | NULL         |   19000.00 |    403 |         3 |
| 13 | 程咬金     | male   |  18 | 1997-03-12 | operation | NULL         |   20000.00 |    403 |         3 |
| 10 | 星星       | female |  18 | 2016-05-13 | sale      | NULL         |    3000.29 |    402 |         2 |
|  9 | 丁丁       | female |  18 | 2011-03-12 | sale      | NULL         |    1000.37 |    402 |         2 |
|  5 | jinxin     | male   |  18 | 1900-03-01 | teacher   | NULL         |   30000.00 |    401 |         1 |
|  4 | jingliyang | female |  18 | 2011-02-11 | teacher   | NULL         |    9000.00 |    401 |         1 |
| 12 | 张野       | male   |  28 | 2016-03-11 | operation | NULL         |   10000.13 |    403 |         3 |
|  3 | liwenzhou  | male   |  28 | 2012-11-01 | teacher   | NULL         |    2100.00 |    401 |         1 |
| 11 | 格格       | female |  28 | 2017-01-27 | sale      | NULL         |    4000.33 |    402 |         2 |
|  8 | 丫丫       | female |  38 | 2010-11-01 | sale      | NULL         |    2000.35 |    402 |         2 |
|  7 | 歪歪       | female |  48 | 2015-03-11 | sale      | NULL         |    3000.13 |    402 |         2 |
|  6 | 成龙       | male   |  48 | 2010-11-11 | teacher   | NULL         |   10000.00 |    401 |         1 |
|  2 | yuanhao    | male   |  73 | 2014-07-01 | teacher   | NULL         |    3500.00 |    401 |         1 |
|  1 | alex       | male   |  78 | 2015-03-02 | teacher   | NULL         | 1000000.31 |    401 |         1 |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
16 rows in set (0.00 sec)

降序 desc

mysql> select * from employee order by age desc;
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| id | name       | sex    | age | hire_date  | post      | post_comment | salary     | office | depart_id |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
|  1 | alex       | male   |  78 | 2015-03-02 | teacher   | NULL         | 1000000.31 |    401 |         1 |
|  2 | yuanhao    | male   |  73 | 2014-07-01 | teacher   | NULL         |    3500.00 |    401 |         1 |
|  7 | 歪歪       | female |  48 | 2015-03-11 | sale      | NULL         |    3000.13 |    402 |         2 |
|  6 | 成龙       | male   |  48 | 2010-11-11 | teacher   | NULL         |   10000.00 |    401 |         1 |
|  8 | 丫丫       | female |  38 | 2010-11-01 | sale      | NULL         |    2000.35 |    402 |         2 |
|  3 | liwenzhou  | male   |  28 | 2012-11-01 | teacher   | NULL         |    2100.00 |    401 |         1 |
| 12 | 张野       | male   |  28 | 2016-03-11 | operation | NULL         |   10000.13 |    403 |         3 |
| 11 | 格格       | female |  28 | 2017-01-27 | sale      | NULL         |    4000.33 |    402 |         2 |
| 14 | 程咬银     | female |  18 | 2013-03-11 | operation | NULL         |   19000.00 |    403 |         3 |
| 15 | 程咬铜     | male   |  18 | 2015-04-11 | operation | NULL         |   18000.00 |    403 |         3 |
| 13 | 程咬金     | male   |  18 | 1997-03-12 | operation | NULL         |   20000.00 |    403 |         3 |
| 10 | 星星       | female |  18 | 2016-05-13 | sale      | NULL         |    3000.29 |    402 |         2 |
|  9 | 丁丁       | female |  18 | 2011-03-12 | sale      | NULL         |    1000.37 |    402 |         2 |
|  5 | jinxin     | male   |  18 | 1900-03-01 | teacher   | NULL         |   30000.00 |    401 |         1 |
|  4 | jingliyang | female |  18 | 2011-02-11 | teacher   | NULL         |    9000.00 |    401 |         1 |
| 16 | 程咬铁     | female |  18 | 2014-05-12 | operation | NULL         |   17000.00 |    403 |         3 |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
16 rows in set (0.00 sec)

按多列排序:先按照age升序 排序，如果年龄age相同情况下，年龄分不出胜负情况下 ，则按照id  降序排序

mysql> select * from employee order by age asc,id desc;
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| id | name       | sex    | age | hire_date  | post      | post_comment | salary     | office | depart_id |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
| 16 | 程咬铁     | female |  18 | 2014-05-12 | operation | NULL         |   17000.00 |    403 |         3 |
| 15 | 程咬铜     | male   |  18 | 2015-04-11 | operation | NULL         |   18000.00 |    403 |         3 |
| 14 | 程咬银     | female |  18 | 2013-03-11 | operation | NULL         |   19000.00 |    403 |         3 |
| 13 | 程咬金     | male   |  18 | 1997-03-12 | operation | NULL         |   20000.00 |    403 |         3 |
| 10 | 星星       | female |  18 | 2016-05-13 | sale      | NULL         |    3000.29 |    402 |         2 |
|  9 | 丁丁       | female |  18 | 2011-03-12 | sale      | NULL         |    1000.37 |    402 |         2 |
|  5 | jinxin     | male   |  18 | 1900-03-01 | teacher   | NULL         |   30000.00 |    401 |         1 |
|  4 | jingliyang | female |  18 | 2011-02-11 | teacher   | NULL         |    9000.00 |    401 |         1 |
| 12 | 张野       | male   |  28 | 2016-03-11 | operation | NULL         |   10000.13 |    403 |         3 |
| 11 | 格格       | female |  28 | 2017-01-27 | sale      | NULL         |    4000.33 |    402 |         2 |
|  3 | liwenzhou  | male   |  28 | 2012-11-01 | teacher   | NULL         |    2100.00 |    401 |         1 |
|  8 | 丫丫       | female |  38 | 2010-11-01 | sale      | NULL         |    2000.35 |    402 |         2 |
|  7 | 歪歪       | female |  48 | 2015-03-11 | sale      | NULL         |    3000.13 |    402 |         2 |
|  6 | 成龙       | male   |  48 | 2010-11-11 | teacher   | NULL         |   10000.00 |    401 |         1 |
|  2 | yuanhao    | male   |  73 | 2014-07-01 | teacher   | NULL         |    3500.00 |    401 |         1 |
|  1 | alex       | male   |  78 | 2015-03-02 | teacher   | NULL         | 1000000.31 |    401 |         1 |
+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+
16 rows in set (0.00 sec)

按单列排序
    SELECT * FROM employee ORDER BY salary;
    SELECT * FROM employee ORDER BY salary ASC;
    SELECT * FROM employee ORDER BY salary DESC;

按多列排序:先按照age排序，如果年纪相同，则按照薪资排序
    SELECT * from employee
        ORDER BY age,
        salary DESC;

1. 查询所有员工信息，先按照age升序排序，如果age相同则按照hire_date降序排序

 select * from employee ORDER BY age asc,hire_date desc;



2. 查询各岗位平均薪资大于10000的岗位名、平均工资,结果按平均薪资升序排列

select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) asc;
+-----------+---------------+
| post      | avg(salary)   |
+-----------+---------------+
| operation |  16800.026000 |
| teacher   | 151842.901429 |
+-----------+---------------+



3. 查询各岗位平均薪资大于10000的岗位名、平均工资,结果按平均薪资降序排列

select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) desc;
+-----------+---------------+
| post      | avg(salary)   |
+-----------+---------------+
| teacher   | 151842.901429 |
| operation |  16800.026000 |
+-----------+---------------+

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