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MySQL, plusieurs lignes pour séparer les champs

Il vous manque juste un groupe par :)

SELECT PartNumber,
  MAX(IF (Priority = 0, SupName, NULL)) AS Sup1,
  MAX(IF (Priority = 1, SupName, NULL)) AS Sup2,
  MAX(IF (Priority = 2, SupName, NULL)) AS Sup3
FROM SupXref
GROUP BY PartNumber

Modifier :

Après avoir joué pendant un certain temps, je pense avoir trouvé la première solution que vous recherchez. Essayez-le :)

SELECT partnumber,
  COALESCE(Sup1, COALESCE(Sup2, Sup3)) AS Supp1,
  IF (Sup1 IS NULL, IF (Sup2 IS NULL, NULL, Sup3), COALESCE(Sup2, Sup3)) AS Supp2,
  IF (Sup1 IS NULL, NULL, IF (Sup2 IS NULL, NULL, Sup3)) AS Supp3
FROM (
  SELECT PartNumber,
    MAX(IF (Priority = 0, SupName, NULL)) AS Sup1,
    MAX(IF (Priority = 1, SupName, NULL)) AS Sup2,
    MAX(IF (Priority = 2, SupName, NULL)) AS Sup3
  FROM SupXref
  GROUP BY PartNumber
) AS S

Pour le tableau suivant :

+------------+----------+---------+
| PARTNUMBER | PRIORITY | SUPNAME |
+------------+----------+---------+
| a1         |        2 | Three   |
| a2         |        1 | Two     |
| a3         |        2 | Three   |
| a3         |        1 | Two     |
| a4         |        0 | One     |
| a5         |        0 | One     |
| a5         |        2 | Three   |
| a6         |        0 | One     |
| a6         |        1 | Two     |
| a7         |        0 | One     |
| a7         |        1 | Two     |
| a7         |        2 | Three   |
+------------+----------+---------+

Les données sont transformées en ceci :

+------------+------+------+-------+
| PARTNUMBER | SUP1 | SUP2 | SUP3  |
+------------+------+------+-------+
| a1         |      |      | Three |
| a2         |      | Two  |       |
| a3         |      | Two  | Three |
| a4         | One  |      |       |
| a5         | One  |      | Three |
| a6         | One  | Two  |       |
| a7         | One  | Two  | Three |
+------------+------+------+-------+

Et enfin dans ceci :

+------------+-------+-------+-------+
| PARTNUMBER | SUPP1 | SUPP2 | SUPP3 |
+------------+-------+-------+-------+
| a1         | Three |       |       |
| a2         | Two   |       |       |
| a3         | Two   | Three |       |
| a4         | One   |       |       |
| a5         | One   | Three |       |
| a6         | One   | Two   |       |
| a7         | One   | Two   | Three |
+------------+-------+-------+-------+