Question

我有一个包含应用统计信息的表格，我们说这些列是os_version和app_id（简化）。我想列出某个应用程序的所有操作系统版本，对于每个操作系统版本，我想看到一些至少包含此操作系统版本的记录。示例数据：

app1 1.0
app1 2.0
app2 1.0

现在app1我希望看到：

version | score | comments
--------+-------+---------
1.0     | 2     | there are two records having OS at least 1.0
2.0     | 1     | there is just one record with OS at least 2.0

现在，请原谅我无知的SQL，但我已经提出了这个问题：

SELECT
    os_version,
    -- number_of_records_having_at_least_this_version / number_of_all_records
    (SELECT COUNT(*) FROM stats WHERE app_id='app1' AND os_version >= outer.os_version)/ 
        (SELECT COUNT(*) FROM stats WHERE app_id='app1') AS score
FROM (SELECT * FROM stats WHERE app_id='app1') AS outer
GROUP BY os_version;

这很疯狂，因为我必须按应用ID过滤三次。是否可以先按应用ID进行过滤，然后使用生成的行集进行进一步操作？没有临时表？在SQLite？类似的东西：

SELECT
    os_version,
    (SELECT COUNT(*) FROM filtered WHERE os_version >= filtered.os_version)/
        (SELECT COUNT(*) FROM filtered) AS score
FROM (SELECT * FROM stats WHERE app_id='app1') AS filtered
GROUP BY os_version;

......遗憾的是，这不起作用。

Answer 1

我认为，如果我已经正确地理解了这个问题，那么这样的事情应该可以解决问题..

SELECT
    s1.app_id,
    s1.os_version,
    count(*)
FROM stats s1 INNER JOIN stats s2 ON s1.app_id = s2.app_id 
                                  AND s2.os_version >= s1.os_version
GROUP BY s1.app_id, s1.os_version

编辑：这会返回app_id所展示的结果（与问题中的示例查询一样）

SELECT
    s1.app_id,
    s1.os_version,
    count(*)
FROM stats s1 INNER JOIN stats s2 ON s1.app_id = s2.app_id 
                                  AND s2.os_version >= s1.os_version
WHERE s1.app_id = 'app1'
GROUP BY s1.app_id, s1.os_version

EDIT2：

SELECT
    s1.app_id,
    s1.os_version,
    count(*)
FROM stats s1 INNER JOIN stats s2 ON s1.app_id = s2.app_id 
                                  AND s2.os_version >= s1.os_version
                                  AND s1.app_id = 'app1'
GROUP BY s1.app_id, s1.os_version

EDIT3：绕过2.11＆lt; 2.7问题

SELECT
    s1.app_id,
    s1.os_version,
    count(*)
FROM stats s1 INNER JOIN stats s2 ON s1.app_id = s2.app_id 
              AND CAST(REPLACE(s2.os_version, '.', '') TO INTEGER) >= 
                  CAST(REPLACE(s1.os_version, '.', '') TO INTEGER)
              AND s1.app_id = 'app1'
GROUP BY s1.app_id, s1.os_version

如何在不重复自己的情况下对数据子集进行SQL查询？

1 个答案: