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这有点难以描述，但是我有一个 postgresql 9.1 表（planet_osm_roads）。我的查询是

SELECT
    osm_id, name, highway, way, md5(astext(way)) AS md5
FROM planet_osm_roads
WHERE highway IS NOT NULL
AND md5(astext(way)) IN (
    SELECT DISTINCT md5(astext(way))
    FROM planet_osm_roads
    WHERE highway IS NOT NULL
    GROUP BY md5
    HAVING count(osm_id) > 1
)
ORDER BY osm_id

结果是

  osm_id  | name |    highway    |       ...way ...  |               md5                
----------+------+---------------+-------...----...--+----------------------------------
 -1641383 |      | motorway      | 010200...CA96...0 | 04b4336b997e7ea9d99208bd487bbe7d
 -1641383 |      | motorway      | 010200...EC3E...0 | ae945148417ada285130c59277c48a25
 -1641383 |      | motorway      | 010200...7BF6...0 | 5c5a1b8ae40c1b7f24e293a012ad2add
 23133731 |      | motorway_link | 010200...EC3E...0 | ae945148417ada285130c59277c48a25
 31309105 |      | motorway      | 010200...7BF6...0 | 5c5a1b8ae40c1b7f24e293a012ad2add
 49339926 |      | motorway      | 010200...CA96...0 | 04b4336b997e7ea9d99208bd487bbe7d
(6 rows)

我想要一个包含 3 行（每个 md5 哈希一个）和任何其他相应行的结果。因此，“ae945148417ada285130c59277c48a25”的有效行可能包含 osm_id-highway 对“-1641383”和“motorway”或“23133731”和“motorway_link”——我不介意并且认为两者都是正确的。

我该如何解决这个问题以及如何调用所需的操作/技术？所以我下次知道如何将其称为要搜索的内容。

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1 回答 1

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select
    md5(astext(way)) as md5,
    min(osm_id) osm_id,
    min(name) name,
    min(highway) highway,
    min(way) way
from planet_osm_roads
where highway is not null
group by 1
having count(osm_id) > 1
于 2013-03-01T12:16:45.937 回答