SQL仅选择具有Where Condition的列上具有最小值的行

Question

表:

| id | productId | orderIndex | rejected |
------------------------------------------
| 1  |  1        |   0        |   1      |
| 2  |  1        |   1        |   0      |
| 3  |  1        |   2        |   0      |
| 4  |  2        |   0        |   0      |
| 5  |  2        |   1        |   1      |
| 6  |  3        |   0        |   0      |

如何为每个productId选择一行,并且最小orderIndex不被拒绝？

预期结果:

| id | productId | orderIndex | rejected |
------------------------------------------
| 2  |  1        |   1        |   0      |
| 4  |  2        |   0        |   0      |
| 6  |  3        |   0        |   0      |

我尝试了这个查询,但没有收到正确的结果:

SELECT id, productId, min(orderIndex)
FROM table
WHERE rejected = 0
GROUP BY productId

这个也不起作用:

SELECT id, productId, min(orderIndex)
FROM (
    SELECT id, productId, orderIndex
    FROM table
    WHERE rejected = 0
) t
GROUP BY productId

Answer 1

您可以从选择未被拒绝的产品的最小orderIndex开始,如下所示:

SELECT productId, MIN(orderIndex)
FROM myTable
WHERE rejected = 0
GROUP BY productId;

完成后,您可以在productId和minOrderIndex匹配的条件下将其与原始表连接:

SELECT m.id, m.productId, m.orderIndex
FROM myTable m
JOIN(
  SELECT productId, MIN(orderIndex) AS minOrderIndex
  FROM myTable
  WHERE rejected = 0
  GROUP BY productId) tmp ON tmp.productId = m.productId AND tmp.minOrderIndex = m.orderIndex;

我的查询假设没有重复(productId,orderIndex)对.只要那些不存在,这将工作得很好.这是一个SQL小提琴示例.