---
{
    "title": "GROUP BY",
    "language": "en"
}
---

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# GROUP BY

## description

  GROUP BY `GROUPING SETS` ｜ `CUBE` ｜ `ROLLUP` is an extension to  GROUP BY clause. This syntax lets you define multiple groupings in the same query. GROUPING SETS produce a single result set that is equivalent to a UNION ALL of differently grouped rows
  For example GROUPING SETS clause:

  ```
  SELECT a, b, SUM( c ) FROM tab1 GROUP BY GROUPING SETS ( (a, b), (a), (b), ( ) );
  ```

  This statement is equivalent to:

  ```
  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)` indicates whether a specified column expression in a GROUP BY list is aggregated or not. GROUPING returns 1 for aggregated or 0 for not aggregated in the result set.

  `GROUPING_ID(expr  [ , expr [ , ... ] ])` describes which of a list of expressions are grouped in a row produced by a GROUP BY query. The GROUPING_ID function simply returns the decimal equivalent of the binary value formed as a result of the concatenation of the values returned by the GROUPING functions.

### 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` is a set of expression or column  or it's alias appearing in the query block’s SELECT list. `groupSet ::= { ( expr  [ , expr [ , ... ] ] )}`

  `expr`  is expression or column  or it's alias appearing in the query block’s SELECT list.

### Note

  doris supports PostgreSQL like syntax, for example:

  ```
  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)` is equivalent to `GROUPING SETS` as follows:

  ```
  GROUPING SETS (
  (a,b,c),
  ( a, b ),
  ( a),
  ( )
  )
  ```

  `CUBE ( a, b, c )` is equivalent to `GROUPING SETS` as follows:

  ```
  GROUPING SETS (
  ( a, b, c ),
  ( a, b ),
  ( a,    c ),
  ( a       ),
  (    b, c ),
  (    b    ),
  (       c ),
  (         )
  )
  ```

## example

  This is a simple example

  ```
  > 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