📅 最后修改于: 2020-12-29 04:36:45 🧑 作者: Mango
SQL ORDER BY子句用于根据一个或多个列以升序或降序对数据进行排序。默认情况下，某些数据库将查询结果按升序排序。
用于对结果进行升序或降序排序的ORDER BY子句的基本语法如下-
SELECT column-list
FROM table_name
[WHERE condition]
[ORDER BY column1, column2, .. columnN] [ASC | DESC];
您可以在ORDER BY子句中使用多个列。确保无论您要使用什么列进行排序，该列都应在column-list中。
考虑具有以下记录的CUSTOMERS表-
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 3 | kaushik | 23 | Kota | 2000.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 6 | Komal | 22 | MP | 4500.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
+----+----------+-----+-----------+----------+
以下是一个示例，该示例将按NAME和SALARY的升序对结果进行排序。
SQL> SELECT * FROM CUSTOMERS
ORDER BY NAME, SALARY;
这将产生以下结果-
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 3 | kaushik | 23 | Kota | 2000.00 |
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 6 | Komal | 22 | MP | 4500.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
+----+----------+-----+-----------+----------+
以下代码块有一个示例，该示例将按NAME的降序对结果进行排序。
SQL> SELECT * FROM CUSTOMERS
ORDER BY NAME DESC;
这将产生以下结果-
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
| 6 | Komal | 22 | MP | 4500.00 |
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 3 | kaushik | 23 | Kota | 2000.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
+----+----------+-----+-----------+----------+
要以自己的首选顺序获取行，使用的SELECT查询将如下所示-
SQL> SELECT * FROM CUSTOMERS
ORDER BY (CASE ADDRESS
WHEN 'DELHI' THEN 1
WHEN 'BHOPAL' THEN 2
WHEN 'KOTA' THEN 3
WHEN 'AHMEDABAD' THEN 4
WHEN 'MP' THEN 5
ELSE 100 END) ASC, ADDRESS DESC;
这将产生以下结果-
+----+----------+-----+-----------+----------+
| ID | NAME | AGE | ADDRESS | SALARY |
+----+----------+-----+-----------+----------+
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 3 | kaushik | 23 | Kota | 2000.00 |
| 6 | Komal | 22 | MP | 4500.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
+----+----------+-----+-----------+----------+
这将首先按照您自己的偏好oorder中的ADDRESS对客户进行排序，并对其余地址按照自然顺序进行排序。同样，其余地址将按相反的字母顺序排序。