Impala Having
Impala 中的
Having 子句使您能够指定条件来过滤哪些组结果出现在最终结果中。
通常，
Having 子句与
group by 子句一起使用；它将条件放在由 GROUP BY 子句创建的组上。
语法
以下是
Having子句的语法。
select * from table_name ORDER BY col_name [ASC|DESC] [NULLS FIRST|NULLS LAST]
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 |
+----+----------+-----+-------------+--------+
| 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 |
| 7 | ram | 25 | chennai | 23000 |
| 8 | rahim | 22 | vizag | 31000 |
| 9 | robert | 23 | banglore | 28000 |
+----+----------+-----+-----------+--------+
Fetched 9 row(s) in 0.51s
以下是在 Impala 中使用
Having 子句的示例-
[quickstart.cloudera:21000] > select max(salary) from customers group by age having max(salary) > 20000;
此查询最初按年龄对表进行分组，并选择每个组的最高工资并显示那些大于 20000 的工资，如下所示。
20000
+-------------+
| max(salary) |
+-------------+
| 30000 |
| 35000 |
| 40000 |
| 32000 |
+-------------+
Fetched 4 row(s) in 1.30s
