Sql 查询：下一个最后一行

Question

我有这样的表 Customer 和 Calls：

客户表：

• CustomerId：唯一标识符
• 企业名称：nvarchar(MAX)

来电表：

• CallId：唯一标识符
• 呼叫日期：日期时间
• 客户 ID：唯一标识符
• 状态：int（呼叫已接听或未接听）

我想获取所有带有最后一次调用和下一次调用列的客户。

Last Called 是状态 = 1 的最后一次调用。Next Call 是状态 = 0 和 Calldate > now 日期的调用。如果他们没有，则为 Null。这是一个非工作示例，只是为了显示格式

Select * 
From Customers,
       Calls.CallId as LastCalledId   
       Calls.CallDate as LastCalledDate
       Calls.CallId as NextCallId
       Calls.CallDate as NextCallDate
LEFT JOIN 
    Calls ON Customers.CustomerId = Calls.CustomerId

我该怎么做？

Answer 1

这是你的意思吗？

更新

select c.id
, lastcall.calldate
, lastcall.id
, firstcall.calldate
, firstcall.id
from @customers c
outer apply (select top 1 calls.calldate, calls.id from @calls calls where calls.custid = c.id and calldate < getdate() order by calldate desc) lastcall(calldate, id)
outer apply (select top 1 calls.calldate, calls.id from @calls calls where calls.custid = c.id and calldate >= getdate() order by calldate asc) firstcall(calldate, id)

原答案：

select c.id
, answered.calldate LastCalledDate
, answered.id LastCalledID
, unaswered.calldate NextCalledDate
, unaswered.id NextCalledID
from @customers c
left join @calls answered ON answered.custid = c.id AND status = 1
left join @calls unaswered ON unaswered.custid = c.id AND unaswered.status = 0 and unaswered.calldate > getdate()

Answer 2

您可以使用 LEFT JOIN 中的 WHERE 子句来获取所需的数据行。在这里您可以使用 Calls.status = 0 或 1 的 where 子句（根据您的要求)

Answer 3

由于您没有为示例数据提供 DDL 和 DML，我无法测试我的答案，因此不能保证会产生预期的结果。
话虽如此，这是我的尝试，应该适用于 2008 或更高版本。

使用 cte 计算每个客户的最后一次接听电话（假设 calldate 是唯一的）和几个左连接我想出了这个：

;WITH LastCall AS
(
    SELECT  CustomerId,
            CallId,
            CallDate
    FROM Calls t0
    WHERE [Status] = 1
    AND CallDate = 
    (
        SELECT MAX(CallDate)
        FROM Calls t1
        WHERE [Status] = 1
        AND t1.CustomerId = t0.CustomerId
    )
)

SELECT  cu.CustomerId, 
        cu.Name,
        lc.CallId as LastCalledId,
        lc.CallDate as LastCalledDate,
        nc.CallId as NextCallId,
        nc.CallDate as NextCallDate
FROM Customers as cu
LEFT JOIN LastCall lc ON cu.CustomerId = lc.CustomerId 
LEFT JOIN Calls nc ON cu.CustomerId = nc.CustomerId AND nc[Status] = 0 AND nc.CallDate > GETDATE()

请注意，对于 2012 及更高版本，您可能可以使用 FIRST_VALUE 或 LAST_VALUE 内置函数。

Answer 4

您可以在连接查询中使用AND。然后订购电话并获得最后一个有限制的电话。

SELECT * 
FROM Customers,
       Calls.CallId as LastCalledId   
       Calls.CallDate as LastCalledDate
       Calls.CallId as NextCallId
LEFT JOIN 
    Calls ON (Customers.CustomerId = Calls.CustomerId AND Calls.Status = 1)
ORDER BY Calls.CallDate DESC
UNION
SELECT * 
FROM Customers,
       Calls.CallId as LastCalledId   
       Calls.CallId as NextCallId
       Calls.CallDate as NextCallDate
LEFT JOIN 
    Calls ON (Customers.CustomerId = Calls.CustomerId AND Calls.Status = 0 AND CallDate > NOW())
ORDER BY Calls.CallDate DESC;

Answer 5

您可以使用不同的方式来做到这一点：

    Select cu.CustomerId,LastCall.Callid,LastCall.calldate,NextCall.Callid,NextCall.calldate from Customers cu,
    (select max(callid) Callid,max(calldate) calldate,CustomerId from Calls c where status = 1 group by CustomerId) LastCall,
    (select max(callid) Callid,max(calldate) calldate,CustomerId from Calls c where status = 0 and calldate > sysdate group by CustomerId) NextCall
    where cu.CustomerId = LastCall.CustomerId and cu.CustomerId = NextCall.CustomerId
    order by 1

Or by replacing in your query :

    Select (select max(callid) from Calls c where c.CustomerId = Cu.CustomerId and status = 1) as LastCalledId,
       (select max(CallDate) from Calls c where c.callid = (select max(callid) from Calls c where c.CustomerId = Cu.CustomerId and status = 1)) as LastCalledDate,
       (select max(callid) from Calls c where c.CustomerId = Cu.CustomerId and status = 0 and CallDate > sysdate ) as NextCallId,
       (select max(CallDate) from Calls c where c.callid = (select max(callid) from Calls c where c.CustomerId = Cu.CustomerId and status = 0 and CallDate > sysdate )) as NextCallDate 
    From Customers Cu,Calls c ON Cu.CustomerId = c.CustomerId