Sql server 连接表时在WHERE子句中使用子查询和筛选器

我得到一个没有数据的输出。子查询不会与WHERE子句中的其他筛选器一起运行。我不确定我做错了什么。有人能帮忙吗

如果您试图从

SecurityPrices

中获取每个

Ticker

的最新行，一个选项是使用

cross apply（）

：

---

您没有得到结果，因为

max（QuoteDateTime）

记录没有

SecurityTypeName='REIT'

。我想您需要这个

SecurityTypeName

的

max（QuoteDateTime）

，因此这可以通过内部连接来完成

select --distinct /* distinct not needed if `Ticker` is unique on `smd`
   smd.Ticker
 , sp.SecurityID
 , sp.ClosePrice
 , sp.QuoteDateTime
from [Hub].[SecurityMaster].[SecurityMasterDetails] as smd
  cross apply (
    select top 1 
        i.SecurityID
      , i.ClosePrice
      , i.QuoteDateTime
    from [Hub].[SecurityMaster].[SecurityPrices] i
    where i.SecurityID = smd.SecurityID
    order by i.QuoteDateTime desc
    ) as sp
where SecurityTypeName = 'REIT' /* which table does this column belong to? */

编辑

我怀疑你的数据没有你认为的那样。以下是您可以检查的方式

SELECT DISTINCT
    (t1.Ticker),
    t2.SecurityID,
    t2.ClosePrice,
    t2.QuoteDateTime 
FROM [Hub].[SecurityMaster].[SecurityMasterDetails] as t1 
    INNER JOIN [Hub].[SecurityMaster].[SecurityPrices] as t2 
    ON t2.SecurityID =t1.SecurityID 
    INNER JOIN 
    (SELECT max(QuoteDateTime) DT FROM [Hub].[SecurityMaster].[SecurityPrices]) P on P.DT =  t2.QuoteDateTime
WHERE SecurityTypeName = 'REIT'

---

由于第一个查询中返回的SecurityID不在第二个查询结果集中，因此将得到NULL结果

我想你的问题是

--Find the SecurityID that matches the max date
SELECT 
    SecurityID , 
    max(QuoteDateTime) DT 
FROM [Hub].[SecurityMaster].[SecurityPrices]
GROUP BY SecurityID

--I'm betting this ID isn't in your SecurityMasterDetails where the Type is REIT
SELECT DISTINCT
    SecurityID
FROM SecurityMasterDetails
WHERE SecurityTypeName = 'REIT'

---

所以您想做什么？在join和where子句之后可以返回结果的所有表中都有有效数据吗？很抱歉，SecurityTypeName取自表t1-[Hub].[SecurityMaster].[SecurityMasterDetails]问题是，数据库中的日期没有按照最近的日期排序。很抱歉，我之前没有正确指定它，QuoteDateTime和SecurityTypeName不是来自同一个表。我不明白为什么，但我的输出中没有任何数据。原因与@SmithaShivakumar之前相同。max（QuoteDateTime）记录的SecurityID不是REIT SecurityID。啊！你建议我做什么？检查我刚做的编辑。您的查询运行正常，因为所有这些查询都是正确的。您不能让数据集返回不存在或不符合@SmithaShivakumar条件的内容

--Find the SecurityID that matches the max date
SELECT 
    SecurityID , 
    max(QuoteDateTime) DT 
FROM [Hub].[SecurityMaster].[SecurityPrices]
GROUP BY SecurityID

--I'm betting this ID isn't in your SecurityMasterDetails where the Type is REIT
SELECT DISTINCT
    SecurityID
FROM SecurityMasterDetails
WHERE SecurityTypeName = 'REIT'

SELECT DISTINCT TOP 1 WITH TIES 
                      t1.Ticker,
                      t2.SecurityID,
                      t2.ClosePrice,
                      t2.QuoteDateTime 
FROM [Hub].[SecurityMaster].[SecurityMasterDetails] as t1 
     INNER JOIN [Hub].[SecurityMaster].[SecurityPrices] as t2 ON t2.SecurityID =t1.SecurityID 
WHERE SecurityTypeName = 'REIT'
ORDER BY t2.QuoteDateTime DESC