SQL-sætning - SQL Matrix

Der er to måder, du kan pivotere på data i MySQL. Hvis du kender værdierne i forvejen (hold), vil du hårdkode værdierne, eller du kan bruge en forberedt erklæring til at generere dynamisk sql.

En statisk version ville være:

select TeamA,
  max(case when TeamB = 'A' then won - lost else 0 end) as A,
  max(case when TeamB = 'B' then won - lost else 0 end) as B,
  max(case when TeamB = 'C' then won - lost else 0 end) as C,
  max(case when TeamB = 'D' then won - lost else 0 end) as D,
  max(case when TeamB = 'E' then won - lost else 0 end) as E
from yourtable
group by TeamA;
 

Se SQL Fiddle with Demo

Hvis du ønsker at bruge en dynamisk version med en forberedt sætning, vil koden være:

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'MAX(CASE WHEN TeamB = ''',
      TeamB,
      ''' THEN won - lost else 0 END) AS `',
      TeamB, '`'
    )
  ) INTO @sql
from
(
  select *
  from yourtable
  order by teamb
) x;

SET @sql 
  = CONCAT('SELECT TeamA, ', @sql, ' 
           from yourtable
           group by TeamA');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
 

Se SQL Fiddle with Demo .

Rediger #1, efter at have tænkt over dette ville jeg faktisk gøre det en smule anderledes. Jeg ville generere en sand matrix for de data, hvor holdene optrådte i både rækken og kolonnen. For at gøre dette skal du først bruge en UNION ALL forespørgsel for at få alle hold i to kolonner:

select teama Team1, teamb Team2,
  won-lost Total
from yourtable
union all
select teamb, teama,
  won-lost
from yourtable
 

Se SQL Fiddle with Demo . Når det er gjort, vil du pivotere dataene:

select Team1,
  coalesce(max(case when Team2 = 'A' then Total end), 0) as A,
  coalesce(max(case when Team2 = 'B' then Total end), 0) as B,
  coalesce(max(case when Team2 = 'C' then Total end), 0) as C,
  coalesce(max(case when Team2 = 'D' then Total end), 0) as D,
  coalesce(max(case when Team2 = 'E' then Total end), 0) as E
from
(
  select teama Team1, teamb Team2,
    won-lost Total
  from yourtable
  union all
  select teamb, teama,
    won-lost
  from yourtable
) src
group by Team1;
 

Se SQL Fiddle with Demo . Hvilket giver et mere detaljeret resultat af: