Jefferson's questions

我对这里的 SQL 感到非常困惑，我有这个示例，我在子查询中使用主查询中的值，然后使用 XML PATH 在日期之间添加逗号。设置是 2 个表，其中一个带有我想串在一起的日期。我不确定为什么子查询 where 语句没有重新调整正确的结果。

http://www.sqlfiddle.com/#!5/5443b/2

设置

CREATE TABLE log
    ([logID] [int] NULL, 
     [LogDate] [datetime] NULL
    )
;

CREATE TABLE logdata
    ([logdataID] [int] NULL, 
     [logID] [datetime] NULL
    )
;
    
INSERT INTO log
    ([logID], [LogDate])
VALUES
    (1, 2021-02-01),
    (1, 2021-02-02),
    (1, 2021-02-03),
    (3, 2021-03-12),
    (4, 2021-02-12)
;

INSERT INTO logdata
    ([logdataID], [logID])
VALUES
    (1, 1),
    (2, 2),
    (3, 3)
;

我的尝试：

Select 
logID,
logdataID
LogDate =  (SELECT ',' + CAST(LogDate AS varchar) FROM log WHERE logID =  logID FOR XML PATH('') )
from logdata

结果

1,2021-02-01,2021-02-02,2021-02-03,2021-03-12,2021-02-12
2,2021-02-01,2021-02-02,2021-02-03,2021-03-12,2021-02-12
3,2021-02-01,2021-02-02,2021-02-03,2021-03-12,2021-02-12

但我想要的结果是：

1 2021-02-01,2021-02-02,2021-02-03
2 2021-03-12
3 2021-02-12

我有一个大约需要 40 秒才能运行的 SQL 语句，我唯一看到的是高哈希匹配和排序。我已将索引添加到临时表，但仍需要很长时间才能完成。

https://www.brentozar.com/pastetheplan/?id=rJ7iMDC9m

SQL Server 执行时间：CPU 时间 = 46735 毫秒，耗用时间 = 9004 毫秒。

SELECT g.CustomerId, g.LogDate
INTO #TempGuidelineLog
FROM vwGuidelineLog g --nolock
where g.LogDate >= '2017-10-01' and g.LogDate < dateadd(day, 1, '2018-09-30')

CREATE NONCLUSTERED INDEX ix_temp1Customer ON #TempGuidelineLog (CustomerId)
INCLUDE ([LogDate])


select
g.*,
a.StateId, 
a.CountryId
into #Temp
from #TempGuidelineLog g
JOIN [vwCustomerAddress] a ON a.CustomerId = g.CustomerId

CREATE NONCLUSTERED INDEX ix_temp1Country ON #Temp (CountryId)
INCLUDE ([CustomerId])

SELECT States=(SELECT Total=COUNT(c.CustomerID), c.StateId, st.Name
,[Distinct] =  COUNT(DISTINCT c.CustomerId)
FROM #Temp c
JOIN [State] st ON st.StateId = c.StateId
where c.CountryId = 1 and st.StateId NOT IN (65,66)
GROUP BY c.StateId, st.Name
ORDER BY 1 DESC
FOR XML PATH('State'),type)

,Dates = (SELECT StartDate = CONVERT(VARCHAR(10), '2017-10-01' , 101), EndDate = CONVERT(VARCHAR(10), '2018-09-30', 101)
FOR XML PATH('Date'),type)

,Countries=(SELECT Total=COUNT(c.CustomerID), co.CountryID, co.Name, ISOCode=co.TwoLetterISOCode
,[Distinct] =  COUNT(DISTINCT c.CustomerId)
FROM #Temp c
JOIN Country co ON co.CountryID = c.CountryId
GROUP BY co.CountryID, co.Name,co.TwoLetterISOCode
ORDER BY 1 DESC
FOR XML PATH('Country'),type)
FOR XML PATH('Report')