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GROUP_CONCAT(expr) returns a string result with the concatenated non-NULL values from a group

The full syntax is as follows: GROUP_CONCAT([DISTINCT] expr [,expr ...]              [ORDER BY {unsigned_integer | col_name | expr}                  [ASC | DESC] [,col_name ...]]              [SEPARATOR str_val]) mysql> CREATE TABLE Employee(     ->     id            int,     ->     first_name    VARCHAR(15),     ->     last_name     VARCHAR(15),     ->     start_date    DATE,     ->     end_date      DATE,     ->     salary        FLOAT(8,2),     ->     city          VARCHAR(10),     ->     description   VARCHAR(15)     -> ); Query OK, 0 rows affected (0.03 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->              values (1,'Jason',    'Martin',  '19960725',  '20060725', 1234.56, 'Toronto',  'Programmer'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(2,'Alison',   'Mathews',  '19760321', '19860221', 6661.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.02 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(3,'James',    'Smith',    '19781212', '19900315', 6544.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(4,'Celia',    'Rice',     '19821024', '19990421', 2344.78, 'Vancouver','Manager'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(5,'Robert',   'Black',    '19840115', '19980808', 2334.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(6,'Linda',    'Green',    '19870730', '19960104', 4322.78,'New York',  'Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(7,'David',    'Larry',    '19901231', '19980212', 7897.78,'New York',  'Manager'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(8,'James',    'Cat',     '19960917',  '20020415', 1232.78,'Vancouver', 'Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id   | first_name | last_name | start_date | end_date   | salary  | city      | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ |    1 | Jason      | Martin    | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto   | Programmer  | |    2 | Alison     | Mathews   | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester      | |    3 | James      | Smith     | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester      | |    4 | Celia      | Rice      | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager     | |    5 | Robert     | Black     | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester      | |    6 | Linda      | Green     | 1987-07-30 | 1996-01-04 | 4322.78 | New York  | Tester      | |    7 | David      | Larry     | 1990-12-31 | 1998-02-12 | 7897.78 | New York  | Manager     | |    8 | James      | Cat       | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester      | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> SELECT city,     -> GROUP_CONCAT(first_name)     -> FROM employee     -> GROUP BY city; +-----------+---------------------------------+ | city      | GROUP_CONCAT(first_name)        | +-----------+---------------------------------+ | New York  | Linda,David                     | | Toronto   | Jason                           | | Vancouver | Alison,James,Celia,Robert,James | +-----------+---------------------------------+ 3 rows in set (0.00 sec) mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.00 sec) Or: mysql> mysql> CREATE TABLE Employee(     ->     id            int,     ->     first_name    VARCHAR(15),     ->     last_name     VARCHAR(15),     ->     start_date    DATE,     ->     end_date      DATE,     ->     salary        FLOAT(8,2),     ->     city          VARCHAR(10),     ->     description   VARCHAR(15)     -> ); Query OK, 0 rows affected (0.01 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->              values (1,'Jason',    'Martin',  '19960725',  '20060725', 1234.56, 'Toronto',  'Programmer'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(2,'Alison',   'Mathews',  '19760321', '19860221', 6661.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(3,'James',    'Smith',    '19781212', '19900315', 6544.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(4,'Celia',    'Rice',     '19821024', '19990421', 2344.78, 'Vancouver','Manager'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(5,'Robert',   'Black',    '19840115', '19980808', 2334.78, 'Vancouver','Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(6,'Linda',    'Green',    '19870730', '19960104', 4322.78,'New York',  'Tester'); Query OK, 1 row affected (0.01 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(7,'David',    'Larry',    '19901231', '19980212', 7897.78,'New York',  'Manager'); Query OK, 1 row affected (0.00 sec) mysql> mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)     ->               values(8,'James',    'Cat',     '19960917',  '20020415', 1232.78,'Vancouver', 'Tester'); Query OK, 1 row affected (0.00 sec) mysql> mysql> select * from Employee; +------+------------+-----------+------------+------------+---------+-----------+-------------+ | id   | first_name | last_name | start_date | end_date   | salary  | city      | description | +------+------------+-----------+------------+------------+---------+-----------+-------------+ |    1 | Jason      | Martin    | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto   | Programmer  | |    2 | Alison     | Mathews   | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester      | |    3 | James      | Smith     | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester      | |    4 | Celia      | Rice      | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager     | |    5 | Robert     | Black     | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester      | |    6 | Linda      | Green     | 1987-07-30 | 1996-01-04 | 4322.78 | New York  | Tester      | |    7 | David      | Larry     | 1990-12-31 | 1998-02-12 | 7897.78 | New York  | Manager     | |    8 | James      | Cat       | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester      | +------+------------+-----------+------------+------------+---------+-----------+-------------+ 8 rows in set (0.00 sec) mysql> mysql> SELECT city,     -> GROUP_CONCAT(DISTINCT first_name     ->              ORDER BY city DESC SEPARATOR ' ')     -> FROM employee     -> GROUP BY city; +-----------+---------------------------------------------------------------------------------+ | city      | GROUP_CONCAT(DISTINCT first_name              ORDER BY city DESC SEPARATOR ' ') | +-----------+---------------------------------------------------------------------------------+ | New York  | David Linda                                                                     | | Toronto   | Jason                                                                           | | Vancouver | Robert Celia James Alison                                                       | +-----------+---------------------------------------------------------------------------------+ 3 rows in set (0.00 sec) mysql> mysql> drop table Employee; Query OK, 0 rows affected (0.01 sec) mysql>