How to concatenate data from one field, in a comma-delimited list, in a many-to-many relationship in MySQL?

    SELECT people.pName,
           GROUP_CONCAT(departments.deptName SEPARATOR ', ') deptName
      FROM people
 LEFT JOIN people_departments 
        ON people.pID = people_departments.pID
 LEFT JOIN departments 
        ON people_departments.deptID = departments.deptID
  GROUP BY people.pID

Output:

+-------+----------------------------------+
| pName | deptName                         |
+-------+----------------------------------+
| James | Engineering, Research            |
| Mary  | Research, Communications         |
| Paul  | Engineering, Research, Marketing |
+-------+----------------------------------+
3 rows in set (0.00 sec)