171 lines
4.7 KiB
Markdown
171 lines
4.7 KiB
Markdown
---
|
|
{
|
|
"title": "GROUP BY",
|
|
"language": "zh-CN"
|
|
}
|
|
---
|
|
|
|
<!--
|
|
Licensed to the Apache Software Foundation (ASF) under one
|
|
or more contributor license agreements. See the NOTICE file
|
|
distributed with this work for additional information
|
|
regarding copyright ownership. The ASF licenses this file
|
|
to you under the Apache License, Version 2.0 (the
|
|
"License"); you may not use this file except in compliance
|
|
with the License. You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing,
|
|
software distributed under the License is distributed on an
|
|
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
|
|
KIND, either express or implied. See the License for the
|
|
specific language governing permissions and limitations
|
|
under the License.
|
|
-->
|
|
|
|
# GROUP BY
|
|
|
|
## description
|
|
|
|
GROUP BY `GROUPING SETS` ｜ `CUBE` ｜ `ROLLUP` 是对 GROUP BY 子句的扩展，它能够在一个 GROUP BY 子句中实现多个集合的分组的聚合。其结果等价于将多个相应 GROUP BY 子句进行 UNION 操作。
|
|
|
|
GROUP BY 子句是只含有一个元素的 GROUP BY GROUPING SETS 的特例。
|
|
例如，GROUPING SETS 语句：
|
|
|
|
```
|
|
SELECT a, b, SUM( c ) FROM tab1 GROUP BY GROUPING SETS ( (a, b), (a), (b), ( ) );
|
|
```
|
|
|
|
其查询结果等价于：
|
|
|
|
```
|
|
SELECT a, b, SUM( c ) FROM tab1 GROUP BY a, b
|
|
UNION
|
|
SELECT a, null, SUM( c ) FROM tab1 GROUP BY a
|
|
UNION
|
|
SELECT null, b, SUM( c ) FROM tab1 GROUP BY b
|
|
UNION
|
|
SELECT null, null, SUM( c ) FROM tab1
|
|
```
|
|
|
|
`GROUPING(expr)` 指示一个列是否为聚合列，如果是聚合列为0，否则为1
|
|
|
|
`GROUPING_ID(expr [ , expr [ , ... ] ])` 与GROUPING 类似， GROUPING_ID根据指定的column 顺序，计算出一个列列表的 bitmap 值，每一位为GROUPING的值. GROUPING_ID()函数返回位向量的十进制值。
|
|
|
|
### Syntax
|
|
|
|
```
|
|
SELECT ...
|
|
FROM ...
|
|
[ ... ]
|
|
GROUP BY [
|
|
, ... |
|
|
GROUPING SETS [, ...] ( groupSet [ , groupSet [ , ... ] ] ) |
|
|
ROLLUP(expr [ , expr [ , ... ] ]) |
|
|
expr [ , expr [ , ... ] ] WITH ROLLUP |
|
|
CUBE(expr [ , expr [ , ... ] ]) |
|
|
expr [ , expr [ , ... ] ] WITH CUBE
|
|
]
|
|
[ ... ]
|
|
```
|
|
|
|
### Parameters
|
|
|
|
`groupSet` 表示 select list 中的列，别名或者表达式组成的集合 `groupSet ::= { ( expr [ , expr [ , ... ] ] )}`
|
|
|
|
`expr` 表示 select list 中的列，别名或者表达式
|
|
|
|
### Note
|
|
|
|
doris 支持类似PostgreSQL 语法, 语法实例如下
|
|
|
|
```
|
|
SELECT a, b, SUM( c ) FROM tab1 GROUP BY GROUPING SETS ( (a, b), (a), (b), ( ) );
|
|
SELECT a, b,c, SUM( d ) FROM tab1 GROUP BY ROLLUP(a,b,c)
|
|
SELECT a, b,c, SUM( d ) FROM tab1 GROUP BY CUBE(a,b,c)
|
|
```
|
|
|
|
`ROLLUP(a,b,c)` 等价于如下`GROUPING SETS` 语句
|
|
|
|
```
|
|
GROUPING SETS (
|
|
(a,b,c),
|
|
( a, b ),
|
|
( a),
|
|
( )
|
|
)
|
|
```
|
|
|
|
`CUBE ( a, b, c )` 等价于如下`GROUPING SETS` 语句
|
|
|
|
```
|
|
GROUPING SETS (
|
|
( a, b, c ),
|
|
( a, b ),
|
|
( a, c ),
|
|
( a ),
|
|
( b, c ),
|
|
( b ),
|
|
( c ),
|
|
( )
|
|
)
|
|
```
|
|
|
|
## example
|
|
|
|
下面是一个实际数据的例子
|
|
|
|
```
|
|
> SELECT * FROM t;
|
|
+------+------+------+
|
|
| k1 | k2 | k3 |
|
|
+------+------+------+
|
|
| a | A | 1 |
|
|
| a | A | 2 |
|
|
| a | B | 1 |
|
|
| a | B | 3 |
|
|
| b | A | 1 |
|
|
| b | A | 4 |
|
|
| b | B | 1 |
|
|
| b | B | 5 |
|
|
+------+------+------+
|
|
8 rows in set (0.01 sec)
|
|
|
|
> SELECT k1, k2, SUM(k3) FROM t GROUP BY GROUPING SETS ( (k1, k2), (k2), (k1), ( ) );
|
|
+------+------+-----------+
|
|
| k1 | k2 | sum(`k3`) |
|
|
+------+------+-----------+
|
|
| b | B | 6 |
|
|
| a | B | 4 |
|
|
| a | A | 3 |
|
|
| b | A | 5 |
|
|
| NULL | B | 10 |
|
|
| NULL | A | 8 |
|
|
| a | NULL | 7 |
|
|
| b | NULL | 11 |
|
|
| NULL | NULL | 18 |
|
|
+------+------+-----------+
|
|
9 rows in set (0.06 sec)
|
|
|
|
> SELECT k1, k2, GROUPING_ID(k1,k2), SUM(k3) FROM t GROUP BY GROUPING SETS ((k1, k2), (k1), (k2), ());
|
|
+------+------+---------------+----------------+
|
|
| k1 | k2 | grouping_id(k1,k2) | sum(`k3`) |
|
|
+------+------+---------------+----------------+
|
|
| a | A | 0 | 3 |
|
|
| a | B | 0 | 4 |
|
|
| a | NULL | 1 | 7 |
|
|
| b | A | 0 | 5 |
|
|
| b | B | 0 | 6 |
|
|
| b | NULL | 1 | 11 |
|
|
| NULL | A | 2 | 8 |
|
|
| NULL | B | 2 | 10 |
|
|
| NULL | NULL | 3 | 18 |
|
|
+------+------+---------------+----------------+
|
|
9 rows in set (0.02 sec)
|
|
```
|
|
|
|
## keyword
|
|
|
|
GROUP, GROUPING, GROUPING_ID, GROUPING_SETS, GROUPING SETS, CUBE, ROLLUP
|