Question

Database: MySQL

Table: Teams

TeamID    INT
TeamName  VARCHAR(20)

Table: People

PeopleID   INT
FirstNameID INT
LastNameID  INT

Table: TeamMembers

TeamID  INT
PeopleID  INT

Table Example: Teams

TeamID       TeamName
1            Team Xstream
2            Team INsanity

Table Example: People

PeopleID   FirstNameID   LastNameID
1          1351          453
2          5463          763
3          976           8762
4          87            784
5          187           465
6          761           566
7          376           2134

Table Example: TeamMembers

TeamID       PeopleID
1            1
1            3
1            7
2            2
2            4
2            5
2            6

Desired Output:

TeamName       TeamMembers
Team Xstream   John Smith/Jane Doe/Daniel Davis
Team INsanity  Sally Sue/Tom Thomas/Jack Jones/Harry Henderson

There will not be a set number of TeamMembers per team, so it’s not like I could have three subqueries because there will only be three team members. I’ve lightly looked online, but I always get the best and most thorough answers here. Any ideas or pointers, please let me know. I honestly have no idea where to begin here. Thanks.

Answer 1

I am guessing that the names of the people are actually stored somewhere considering you are just showing ID numbers as names. But you will want to use both CONCAT() and GROUP_CONCAT() for this result. The first step, will join all of the tables and use the CONCAT() function:

select t.teamname,
 concat(p.FirstNameId, ' ', p.LastNameId) teamMembers
from teams t
left join teammembers m
  on t.teamid = m.teamid
left join people p
  on m.peopleid = p.peopleid;

See SQL Fiddle with Demo, which will produce the result:

|      TEAMNAME | TEAMMEMBERS |
-------------------------------
|  Team Xstream |    1351 453 |
|  Team Xstream |    976 8762 |
|  Team Xstream |    376 2134 |
| Team INsanity |    5463 763 |
| Team INsanity |      87 784 |
| Team INsanity |     187 465 |
| Team INsanity |     761 566 |

Once you have the data, then apply the GROUP_CONCAT() function and GROUP BY the teamname:

select t.teamname,
  group_concat(concat(p.FirstNameId, ' ', p.LastNameId) SEPARATOR '/') teamMembers
from teams t
left join teammembers m
  on t.teamid = m.teamid
left join people p
  on m.peopleid = p.peopleid
group by t.teamname;

See SQL Fiddle with Demo

results:

|      TEAMNAME |                     TEAMMEMBERS |
---------------------------------------------------
| Team INsanity | 761 566/87 784/187 465/5463 763 |
|  Team Xstream |      976 8762/376 2134/1351 453 |