Question

我在两个不同的数据库中有两个表

Database1 - Table1
Database2 - Table2

Table1 Columns: NimID,IDDate,Station
Table2 Columns: XilID,XilDate

Table1                                                   Table2
NimID   IDDate           Station                   XilID       XilDate      
234     2011-04-21       HYD                     234        2011-04-21
237     2011-04-21       CHN                     208        2011-04-21
208     2011-04-21       HYD                     209        2011-04-15
209     2011-04-15       DEL                      218        2011-05-28
                                                             212       2011-03-11

我想知道Table1中有多少ID不在Table2中，其中IDDate = XilDate ='2011-04-21'group by Table1.Station。我在下面进行了查询

select x.Station as Station,
       count(distinct x.NimID) as Difference
from (
      select a.NimID,
             a.IDDate,
             a.Station
      from database1.dbo.table1 a
      where left(cast(a.Date as date),11)='2011-04-21'
 ) as X, (
      select b.XilID,
             b.XILDate 
      from database2.dbo.Table2 b
      where b.XilDate='2011-04-21'
 ) as Y
 where x.NimID not in (y.XilID)
 group by x.Station

但是这个查询会永远运行.. 请记住，这些表来自位于同一服务器上的不同数据库，Table1包含10,000,000条记录，Table2包含大约13,000,000条记录如果错误请更正我的查询或建议我更快的方式

由于

Answer 1

尽量避免从datetime转换为varchar。

  WHERE a.Date >= '2011-04-21'
  AND a.Date < (CAST('2011-04-21' AS datetime) + 1)

Answer 2

DECLARE @date datetime;
SET @date = '20110421';

SELECT
  Station,
  Diff = COUNT(*)
FROM (
  SELECT
    a.NimID,
    a.IDDate,
    a.Station
  FROM database1.dbo.table1 a
    LEFT JOIN database2.dbo.table2 b ON a.NimID = b.XilID AND b.XilDate = @date
  WHERE b.XilID IS NULL
    AND a.IDDate >= @date
    AND a.IDDate < DATEADD(day, 1, @date)
) s
GROUP BY Station

<强>更新

实际上，上述解决方案可以在没有子选择的情况下重写。 subselect是尝试一些想法的结果，我最终放弃了，但是subselect仍然有一些未知的原因。这是一个没有子选择的相同解决方案：

DECLARE @date datetime;
SET @date = '20110421';

SELECT
  a.Station,
  Diff = COUNT(*)
FROM database1.dbo.table1 a
  LEFT JOIN database2.dbo.table2 b ON a.NimID = b.XilID AND b.XilDate = @date
WHERE b.XilID IS NULL
  AND a.IDDate >= @date
  AND a.IDDate < DATEADD(day, 1, @date)
GROUP BY a.Station

Answer 3

尝试以下操作 - 请注意，您似乎正在尝试连接两个表来执行“not in”，这会导致生成速度非常慢且结果集非常错误。

此外，如果IDDate是DATETIME列，那么您最好执行范围检查，例如(a.IDDate >= '2011-04-21' AND a.IDDate < '2011-04-22')。考虑一下 - 如果它是yyyy-MM-dd格式的文本列，那么范围检查也会起作用 - 如果它是具有混合格式日期的文本列，那么请忘记我提到它。

select x.Station as Station,
       count(distinct x.NimID) as Difference
from (
      select a.NimID,
             a.IDDate,
             a.Station
      from database1.dbo.table1 a
      where left(cast(a.IDDate as date),11)='2011-04-21'
 ) as X
 where x.NimID not in (
      select b.XilID
      from database2.dbo.Table2 b
      where b.XilDate='2011-04-21'
 )
 group by x.Station

SQL Query永远运行 - SQL Server 2008

3 个答案: