MariaDB Order By子句

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2023-03-14

在MariaDB数据库中，ORDER BY子句用于按升序或降序对结果集中的记录进行排序。

语法：

SELECT expressions  
FROM tables  
[WHERE conditions]  
ORDER BY expression [ ASC | DESC ];

注意：可以对结果进行排序而不使用ASC/DESC属性。默认情况下，结果将按升序(ASC)排序。

1. ORDER BY子句不使用ASC/DESC属性

在这个示例中，使用具有以下数据的students表：

MariaDB [testdb]> select * from students;
+------------+--------------+-----------------+----------------+
| student_id | student_name | student_address | admission_date |
+------------+--------------+-----------------+----------------+
|          1 | Maxsu        | Haikou          | 2017-01-07     |
|          3 | JMaster      | Beijing         | 2016-05-07     |
|          4 | Mahesh       | Guangzhou       | 2016-06-07     |
|          5 | Kobe         | Shanghai        | 2016-02-07     |
|          6 | Blaba        | Shengzhen       | 2016-08-07     |
|          7 | Maxsu        | Sanya           | 2017-08-08     |
+------------+--------------+-----------------+----------------+
6 rows in set (0.00 sec)

示例

SELECT * FROM students  
WHERE student_name LIKE '%Ma%'  
ORDER BY student_id;

执行上面查询语句，得到以下结果 -

MariaDB [testdb]> SELECT * FROM students
    -> WHERE student_name LIKE '%Ma%'
    -> ORDER BY student_id;
+------------+--------------+-----------------+----------------+
| student_id | student_name | student_address | admission_date |
+------------+--------------+-----------------+----------------+
|          1 | Maxsu        | Haikou          | 2017-01-07     |
|          3 | JMaster      | Beijing         | 2016-05-07     |
|          4 | Mahesh       | Guangzhou       | 2016-06-07     |
|          7 | Maxsu        | Sanya           | 2017-08-08     |
+------------+--------------+-----------------+----------------+
4 rows in set (0.00 sec)

在上面结果集中，可以看到是按student_id字段从小到大(不指定ASC或DESC时，默认使用ASC)来排序的。

2. ORDER BY子句使用DESC属性

示例

SELECT * FROM students  
WHERE student_name LIKE '%Ma%'  
ORDER BY student_id DESC;

执行上面查询语句，得到以下结果 -

MariaDB [testdb]> SELECT * FROM students
    -> WHERE student_name LIKE '%Ma%'
    -> ORDER BY student_id DESC;
+------------+--------------+-----------------+----------------+
| student_id | student_name | student_address | admission_date |
+------------+--------------+-----------------+----------------+
|          7 | Maxsu        | Sanya           | 2017-08-08     |
|          4 | Mahesh       | Guangzhou       | 2016-06-07     |
|          3 | JMaster      | Beijing         | 2016-05-07     |
|          1 | Maxsu        | Haikou          | 2017-01-07     |
+------------+--------------+-----------------+----------------+
4 rows in set (0.00 sec)

在上面结果集中，可以看到是按student_id字段从大到小(指定DESC)来排序的。

3. 按多列排序

假设students表中有两个人的名字是：Maxsu，我们希望先按student_name升序排序，在列的值相同时，再按student_id降序排序，参考以下查询语句 -

SELECT * FROM students  
WHERE student_name LIKE '%Ma%'  
ORDER BY student_name ASC, student_id DESC;

执行上面查询语句，得到以下结果 -