多个group_concat

Question

I am in the process of planning a database for a mysql project and think I need to get this solved before I go any further.

CREATE TABLE ResultsTbl (
    EventID INTEGER,
    MatchNumber INTEGER (9),
    TeamNumber int,
    IndividualName CHAR (100),
    Result char (4)
);

INSERT INTO ResultsTbl VALUES (1,1,1,'individual 1','W');
INSERT INTO ResultsTbl VALUES (1,1,1,'individual 2','W');
INSERT INTO ResultsTbl VALUES (1,1,2,'individual 3','L');
INSERT INTO ResultsTbl VALUES (1,1,2,'individual 4','L');
INSERT INTO ResultsTbl VALUES (1,1,3,'individual 5','L');
INSERT INTO ResultsTbl VALUES (1,1,3,'individual 6','L');
INSERT INTO ResultsTbl VALUES (1,2,1,'individual 7','W');
INSERT INTO ResultsTbl VALUES (1,2,2,'individual 8','L');
INSERT INTO ResultsTbl VALUES (1,3,1,'individual 9','W');
INSERT INTO ResultsTbl VALUES (1,3,1,'individual 10','W');
INSERT INTO ResultsTbl VALUES (1,3,2,'individual 11','L');
INSERT INTO ResultsTbl VALUES (1,3,2,'individual 12','L');

So I have a table which holds data for matches. I need the end result to have one cell for each MatchNumber where the Result = 'W' and one where the Result = 'L', but I need the IndividualNames on the same teams concatenated with a "&". I also need the teams concatenated with a ",".

For the example above, the desired result needs to be as follows:

MatchNumber  |  Winners                      |   Losers 
1            |  Individual 1 & individual 2  |  individual 3 & individual 4, individual 5 & individual 6
2            |  individual 7                 |  individual 8
3            |  individual 9 & individual 10 |  individual 11 & individual 12

So on MatchNumber 1 we have one team in the winners but 2 teams in the losers. The individual within the same teams are concatenated with a "&", and the different teams are concatenated with a ",". Match 2 only has 1 individual on each team, so there are no special characters needed. Match 3 has 1 team of 2 individuals on both the winners and losers, so they are concatenated with a "&" with no need for a ",".

I would love to write what I have failed on but I just can't get any where near what I need to do. I have looked down the road of a group_concat on the teams, then a group_concat on the result, but I can't figure it out.

I wanted to get this dealt with before processing all of the data, so if the table structures need changing to get this done then I am open to suggestions.

Thanks for any help or advice anyone can give.

Answer 1

You need a first set of results by match number, team, and winning type
You need second set of result by match number and winning type

   select 
      MatchNumber,
      group_concat( Winners ) Winners,
      group_concat( Losers ) Losers
   from
      (
         select
          MatchNumber,
          TeamNumber,
          case Result when 'W'
                  then group_concat(IndividualName separator '&') end Winners,
          case Result when 'L'
                  then group_concat(IndividualName separator '&') end Losers,
          group_concat(Result separator '&') r
         from
          Resultstbl 
         group by 
          MatchNumber, TeamNumber
      ) g 
   group by MatchNumber

Answer 2

Give this a bash:

select MatchNumber,
  group_concat(Winners order by TeamNumber),
  group_concat(Losers order by TeamNumber)
from
(
 select MatchNumber,TeamNumber,
  group_concat(case when Result = 'W' then IndividualName end SEPARATOR " & ") as Winners,
  group_concat(case when Result = 'L' then IndividualName end SEPARATOR " & ") as Losers
  from ResultsTbl
 group by MatchNumber, TeamNumber
) t
group by MatchNumber
;