Question

我有一个BLOB列，我希望与其他列同时选择，另一个表中的关联行数COUNT。这就是我所拥有的：

SELECT locations.id, locations.name, photo,
    COUNT(items.id) OVER (PARTITION BY locations.id) AS num_items
FROM locations
LEFT OUTER JOIN items ON locations.id = items.location_id
ORDER BY locations.name ASC

photo是BLOB列。此查询获取了我想要的所有数据，但我看到每个location的 x 行，其中 x 是与item相关联的行数location。

所以我得到了：

id          name          photo          num_items
1           location1                    3
1           location1                    3
1           location1                    3
2           location2                    1
3           location3                    2
3           location3                    2
4           location4                    0

我想要的是什么：

id          name          photo          num_items
1           location1                    3
2           location2                    1
3           location3                    2
4           location4                    0

问题是您无法在DISTINCT列上执行GROUP BY，MIN或BLOB。

Answer 1

我似乎总是在发布后立即找出答案。：P

SELECT location_data.*, photo
FROM (
    SELECT locations.id, locations.name, COUNT(DISTINCT items.id) AS num_items
    FROM locations
    LEFT OUTER JOIN items ON locations.id = items.location_id
    GROUP BY locations.id, locations.name
) location_data
INNER JOIN (
    SELECT locations.id, photo
    FROM locations
) photo_data ON location_data.id = photo_data.id
ORDER BY name ASC

具有COUNT和BLOB列的唯一行 - DB2

1 个答案: