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GROUP_CONCAT

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Concatenates all of the values passed in during aggregation.

Note

This aggregate function is not to be confused with CONCAT, which is a non-aggregate function returning a concatenation of its list of arguments.

Syntax

GROUP_CONCAT( [DISTINCT]
           expression, [ expression, [expression ...]]
           [ORDER BY expression [ASC|DESC]]
           [SEPARATOR string] )

Arguments

  • DISTINCT: optionally filter the result set for only unique sets of expressions

  • expression: any set of expressions. This may be a column name, the result of another function, or a math operation.

  • ORDER BY: optionally sort the result set of the GROUP_CONCAT values in ascending or descending order. By default, the result is sorted in ascending order.

  • SEPARATOR string: by default, the separator character is the comma ,. This argument overrides the default.

Note: You cannot use the DISTINCT keyword with the ORDER BY clause in a GROUP_CONCAT function.

Return Type

The return type is a string. The result is made up of the concatenated non-NULL values from the given group, or NULL if there are no non-NULL values. The variable group_concat_max_len controls the maximum length string this function can return.

For more information on this variable, see the List of Engine Variables.

Examples

CREATE TABLE gc_products (id int, region varchar(30), ship_code varchar(5));
INSERT INTO gc_products VALUES
  (1, 'North', 'A'),
  (2, 'North', 'B'),
  (3, 'South', 'A'),
  (4, 'East', 'A'),
  (5, 'East', 'C'),
  (6, 'West', 'D'),
  (7, 'South', 'A'),
  (8, 'West', 'B');
SELECT GROUP_CONCAT(ship_code) FROM gc_products;
+-------------------------+
| GROUP_CONCAT(ship_code) |
+-------------------------+
| A,B,A,A,C,D,A,B         |
+-------------------------+
SELECT GROUP_CONCAT(DISTINCT ship_code) AS distinct_codes FROM gc_products;
+----------------+
| distinct_codes |
+----------------+
| A,B,C,D        |
+----------------+
SELECT GROUP_CONCAT(DISTINCT ship_code SEPARATOR " ") AS distinct_codes FROM gc_products;
+----------------+
| distinct_codes |
+----------------+
| A B C D        |
+----------------+
SELECT GROUP_CONCAT(first_name, " ", last_name) FROM bffs;
+------------------------------------------+
| GROUP_CONCAT(first_name, " ", last_name) |
+------------------------------------------+
| Cecelia Cruz,Ari Floo,Skylar Rhodes      |
+------------------------------------------+
SELECT dept_id, GROUP_CONCAT(emp_id ORDER BY emp_id) FROM grptable GROUP_BY dept_id;
+---------+--------------------------------------+
| dept_id | GROUP_CONCAT(emp_id ORDER BY emp_id) |
+---------+--------------------------------------+
|       1 | 100                                  |
|       5 | 500,700                              |
|       4 | 300,400                              |
|       6 | 600                                  |
+---------+--------------------------------------+
CREATE TABLE gc_emp_info(emp_id INT, dept_code INT, salary_level INT);


INSERT INTO gc_emp_info VALUES(298, 401, 5), (341, 202, 2), (491, 111, 1);
SELECT GROUP_CONCAT(CONCAT(emp_id, '-', dept_code, '-', salary_level) ORDER BY emp_id DESC, dept_code ASC) FROM gc_emp_info;
+----------------------------------------------------------------+
| GROUP_CONCAT(CONCAT(emp_id, '-', dept_code, '-', salary_level) |
|  ORDER BY emp_id DESC, dept_code ASC)                          |
|  GROUP_CONCAT(first_name, " ", last_name)                      |
+----------------------------------------------------------------+
| 491-111-1,341-202-2,298-401-5                                  |
+----------------------------------------------------------------+

Related Topics

  • JSON_AGG can be used for similar tasks and also supports ORDER BY.

Last modified: June 16, 2023

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