左连接子查询访问

Posted 2023-05-07

【中文标题】左连接子查询访问

【英文标题】：left join subquery access

【发布时间】：2016-08-24 10:26:40

【问题描述】：

以下代码可以正常工作（即不会出错）但是它连接了来自子查询“e”的所有内容。我希望它只返回 [Total Cancellations] 而不是 [Business Unit]

感谢帮助

SELECT *
FROM (SELECT c.*,b.[Total Bookings]
FROM (SELECT DISTINCT a.[business unit], count(a.[lookup_id]) as [Total Colleagues in DMS]
FROM EVERYTHING AS a
GROUP BY a.[business unit]

)  AS c 


LEFT JOIN (SELECT a.[business unit], count(a.[lookup_id]) as [Total Bookings]
FROM EVERYTHING AS a
WHERE a.[session_code]is not null
GROUP BY a.[business unit]

)  AS b ON c.[business unit]=b.[business unit]

)  AS d LEFT JOIN (SELECT a.[business unit], count(a.[lookup_id]) as [Total Cancellations]
FROM EVERYTHING AS a
WHERE a.[Has Booking been cancelled (Yes / No)]=1
group by a.[business unit]

)  AS e ON d.[business unit]=e.[business unit];

    enter code here

【问题讨论】：

您正在使用SELECT *，我希望它会从连接查询中返回 all 列。通过明确提及您要保留的列来限制这一点。

如何在响应中发布代码？谢谢

请不要将您的查询作为评论发布！

什么是访问？您是说 MS Access 吗？标签明确建议不要将 access 用于 MS Office 程序，而应使用 ms-access。也调整标题。

【参考方案1】：

这样试试，

   SELECT d.[business unit]
    ,d.[Total Colleagues in DMS]
    ,d.[Total Bookings]
    ,e.[Total Cancellations]
--,f.columnname
FROM (
    SELECT c.*
        ,b.[Total Bookings]
    FROM (
        SELECT DISTINCT [business unit]
            ,count([lookup_id]) AS [Total Colleagues in DMS]
        FROM EVERYTHING
        GROUP BY [business unit]
        ) c
    LEFT JOIN (
        SELECT [business unit]
            ,count([lookup_id]) AS [Total Bookings]
        FROM EVERYTHING
        WHERE [session_code] IS NOT NULL
        GROUP BY [business unit]
        ) b ON c.[business unit] = b.[business unit]
    ) d
LEFT JOIN (
    SELECT [business unit]
        ,count([lookup_id]) AS [Total Cancellations]
    FROM EVERYTHING
    WHERE [Has Booking been cancelled (Yes / No)] = 1
    GROUP BY [business unit]
    ) e ON d.[business unit] = e.[business unit];
    --LEFT JOIN (....) f ON ...

【讨论】：

太棒了。效果很好。谢谢

您可以投票或选择适合您的答案。

如果我需要进一步添加左连接，我该怎么做？再次感谢

再次感谢您的帮助。我更改了查询并添加了额外的 LEFT JOIN 但它出错了。非常感激。不知道我哪里错了。