mysql - 通过 WHERE 子句选择所有行

Question

我有以下有效的查询(没有“WHERE stats.dt”部分)。我获取所有用户的数据。

我的问题是，这个查询当然只会产生包含 stats.dt > $timestampnow-$maxdays_data) 的用户的行。但我需要所有用户，但仅当 stats.dt 大于 tstamp-maxdays 时才需要获取他们的 SUM(上传)或 SUM(下载)值。具有上传和下载值的其他行(其中 stats.dt 小于我需要的值)可以被忽略。

一个例子是，nodeid 2 的用户不会被选择，因为他的 dt 太小。我确实希望选择用户，但不希望选择数据或上传值(它们可以为 0)。

统计表如下所示

nodeid |    dt      | upload | download
----------------------------------------
1      | 1381699533 | 345345 | 42324234
1      | 1382899152 | 7575   | 574234
1      | 1380699533 | 764534 | 7235232
2      | 1372899152 | 71455  | 124123

我不知道从哪里开始寻找如何解决这个问题，所以也许有人可以给我指出正确的方向。谢谢!

SELECT b.id, b.lastname, b.name, c.balance, a.maxdebt, b.warndata, b.warndownload, b.warnupload, b.warndebt, b.cutoffdata, b.cutoffdownload, b.cutoffupload, b.cutoffdebt, b.data, b.download, b.upload, b.warning, b.access, b.cutoffstop
FROM (
SELECT customers.id AS id, SUM(tariffs.value) AS maxdebt
        FROM tariffs
        LEFT JOIN assignments ON tariffs.id = assignments.tariffid
        RIGHT JOIN customers ON assignments.customerid = customers.id
        GROUP BY id
) a
JOIN (
SELECT customers.id AS id, UPPER(lastname) AS lastname, customers.name AS name, SUM(stats.upload+stats.download) AS data, SUM(stats.download) AS download, SUM(stats.upload) AS upload, customers.cutoffstop, warndata, warndownload, warnupload, warndebt, cutoffdata, cutoffdownload, cutoffupload, cutoffdebt, nodes.warning, nodes.access
        FROM customers
        LEFT JOIN nodes ON customers.id = nodes.ownerid
        LEFT JOIN stats ON nodes.id = stats.nodeid
        LEFT JOIN customerwarnings ON customers.id = customerwarnings.id
        WHERE stats.dt > ($timestampnow-$maxdays_data) 
        GROUP BY id
) b ON a.id = b.id
JOIN (
SELECT customerid, SUM(cash.value) AS balance
        FROM cash
        GROUP BY customerid
) c ON b.id = c.customerid

Answer 1

这是一种蛮力的方法。几乎可以肯定它可以被简化，但是如果不了解更多关于表和外键结构的信息，就很难确定。

我所做的是将 sum(stats.download) 替换为 sum(case when stats.dt > ($timestampnow-$maxdays_data) then s.download end) 和上传类似。我还将 b 上的联接更改为外部联接:

Select
    b.id, 
    b.lastname, 
    b.name, 
    c.balance, 
    a.maxdebt, 
    b.warndata, 
    b.warndownload, 
    b.warnupload, 
    b.warndebt, 
    b.cutoffdata, 
    b.cutoffdownload, 
    b.cutoffupload, 
    b.cutoffdebt, 
    b.data, 
    b.download, 
    b.upload, 
    b.warning, 
    b.access, 
    b.cutoffstop
From (
    Select
        c.id,
        sum(t.value) as maxdebt
    From
        tariffs t
            left join
        assignments a
            on t.id = a.tariffid
            right join 
        customers
            on a.customerid = c.id
        Group by
            c.id
    ) a left outer join (
    Select
        c.id,
        upper(lastname) as lastname,
        c.name,
        sum(s.upload + s.download) as data,
        sum(case when stats.dt > ($timestampnow-$maxdays_data) then s.download end) as download,
        sum(case when stats.dt > ($timestampnow-$maxdays_data) then s.upload end) as upload, 
        c.cutoffstop,
        warndata, 
        warndownload, 
        warnupload,
        warndebt, 
        cutoffdata, 
        cutoffdownload, 
        cutoffupload, 
        cutoffdebt,
        n.warning,
        n.access
    From
        customers c
            left join
        nodes n
            on c.id = n.ownerid
            left join
        stats s
            on n.id = s.nodeid
            left join
        customerwarnings w
            on c.id = w.id
    Group By 
        c.id
    ) b 
        On a.id = b.id
        inner join (
    Select
        customerid, 
        sum(cash.value) as balance
    From
        cash
    Group By
        customerid
    ) c 
    on a.id = c.customerid