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我正在尝试使用 SQL Server 2012加入两个日志表，以便添加每个帐户在记录操作时的状态。

第一个表是根据请求日期( request_date) 和请求接收者( receiver_account_id) 从网站用户（对其他用户）的联系请求日志创建的报告。如果联系请求获得批准，那么也会填充批准日期( approval_date) 列。该表如下所示：

    receiver_account_id    sender_account_id    request_date    approval_date
    13                     19                   2012-08-10      2012-09-01
    13                     21                   2013-05-15      NULL
    17                     19                   2011-09-11      NULL
    25                     44                   2012-11-05      2012-11-07

第二张表主要记录账户的状态变化：

    date        account_id        status
    2011-07-10  13                free
    2012-08-15  13                premium
    2010-12-10  17                free
    2012-05-05  17                premium
    2010-01-20  25                free
    2011-04-10  25                premium
    2012-11-06  25                free

我想加入这两个表，所以我可以得到这样的东西：

    receiver_account_id    sender_account_id    request_date    approval_date    receiver_status_when_received    receiver_status_when_approved
    13                     19                   2012-08-10      2012-09-01       free                             premium  
    13                     21                   2013-05-15      NULL             premium                          NULL
    17                     19                   2011-09-11      NULL             free                             NULL
    25                     44                   2012-11-05      2012-11-07       premium                          free

发件人的状态根本不重要。

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1 回答 1

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尝试这个

;WITH StatusPeriods AS
(
    SELECT account_id, [Status], [date] AS StatusStart, 
        ISNULL((SELECT MIN(Date) FROM status_log nxt WHERE nxt.date > sl.Date AND nxt.account_id = sl.account_id), '2100-1-1') AS StatusEnd
    FROM status_log sl
) 
SELECT request.*, 
    StatusWhenReceived.[Status] AS  receiver_status_when_received, StatusWhenApproved.[Status] AS receiver_status_when_approved
FROM requests 
INNER JOIN  StatusPeriods StatusWhenReceived 
    ON StatusWhenReceived.receiver_account_id = requests.account_id AND requests.request_date between StatusWhenReceived.StatusStart AND StatusWhenReceived.StatusEnd
LEFT  JOIN  StatusPeriods StatusWhenApproved 
    ON StatusWhenApproved.receiver_account_id = requests.account_id AND requests.approval_date between StatusWhenApproved.StatusStart AND StatusWhenApproved.StatusEnd
于 2013-08-07T15:09:19.013 回答