Impala 排序
Impala
ORDER BY 子句用于根据一列或多列按升序或降序对数据进行排序。部分数据库默认按升序对查询结果进行排序。
语法
以下是 ORDER BY 子句的语法。
select * from table_name ORDER BY col_name [ASC|DESC] [NULLS FIRST|NULLS LAST]
您可以分别使用关键字
ASC 或
DESC 按升序或降序排列表格中的数据。
同理，如果我们使用NULLS FIRST，表中所有的空值都排在最上面的几行；如果我们使用NULLS LAST，则包含空值的行将排在最后。
示例
假设我们在数据库
my_db中有一个名为
customers的表，其内容如下-
[quickstart.cloudera:21000] > select * from customers;
Query: select * from customers
+----+----------+-----+-----------+--------+
| id | name | age | address | salary |
+----+----------+-----+-----------+--------+
| 3 | kaushik | 23 | Kota | 30000 |
| 1 | Ramesh | 32 | Ahmedabad | 20000 |
| 2 | Khilan | 25 | Delhi | 15000 |
| 6 | Komal | 22 | MP | 32000 |
| 4 | Chaitali | 25 | Mumbai | 35000 |
| 5 | Hardik | 27 | Bhopal | 40000 |
+----+----------+-----+-----------+--------+
Fetched 6 row(s) in 0.51s
以下是使用
order by 子句按
id's 的升序排列
customers 表中数据的示例。
[quickstart.cloudera:21000] > Select * from customers ORDER BY id asc;
执行时，上述查询产生以下输出。
Query: select * from customers ORDER BY id asc
+----+----------+-----+-----------+--------+
| id | name | age | address | salary |
+----+----------+-----+-----------+--------+
| 1 | Ramesh | 32 | Ahmedabad | 20000 |
| 2 | Khilan | 25 | Delhi | 15000 |
| 3 | kaushik | 23 | Kota | 30000 |
| 4 | Chaitali | 25 | Mumbai | 35000 |
| 5 | Hardik | 27 | Bhopal | 40000 |
| 6 | Komal | 22 | MP | 32000 |
+----+----------+-----+-----------+--------+
Fetched 6 row(s) in 0.56s
同理，您可以使用
order by子句按降序排列
customers表的数据，如下所示。
[quickstart.cloudera:21000] > Select * from customers ORDER BY id desc;
执行时，上述查询产生以下输出。
Query: select * from customers ORDER BY id desc
+----+----------+-----+-----------+--------+
| id | name | age | address | salary |
+----+----------+-----+-----------+--------+
| 6 | Komal | 22 | MP | 32000 |
| 5 | Hardik | 27 | Bhopal | 40000 |
| 4 | Chaitali | 25 | Mumbai | 35000 |
| 3 | kaushik | 23 | Kota | 30000 |
| 2 | Khilan | 25 | Delhi | 15000 |
| 1 | Ramesh | 32 | Ahmedabad | 20000 |
+----+----------+-----+-----------+--------+
Fetched 6 row(s) in 0.54s
