आप बस एक समूह को याद कर रहे हैं :)
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
संपादित करें:
थोड़ी देर खेलने के बाद मुझे लगता है कि मुझे वह पहला समाधान मिल गया है जिसकी आप तलाश कर रहे हैं। इसे आज़माएं :)
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
निम्न तालिका के लिए:
+------------+----------+---------+
| 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 |
+------------+----------+---------+
डेटा इसमें बदल जाता है:
+------------+------+------+-------+
| PARTNUMBER | SUP1 | SUP2 | SUP3 |
+------------+------+------+-------+
| a1 | | | Three |
| a2 | | Two | |
| a3 | | Two | Three |
| a4 | One | | |
| a5 | One | | Three |
| a6 | One | Two | |
| a7 | One | Two | Three |
+------------+------+------+-------+
और अंत में इसमें:
+------------+-------+-------+-------+
| PARTNUMBER | SUPP1 | SUPP2 | SUPP3 |
+------------+-------+-------+-------+
| a1 | Three | | |
| a2 | Two | | |
| a3 | Two | Three | |
| a4 | One | | |
| a5 | One | Three | |
| a6 | One | Two | |
| a7 | One | Two | Three |
+------------+-------+-------+-------+
