SQL Server DISTINCT 分页与 ROW_NUMBER() 不不同

Question

好的，所以基本上我的DISTINCT 使用ROW_NUMBER() 变得无用，我需要避免这种情况，因为它会导致重复的结果（当然除了唯一的数字！）

所以我正在寻找的是一个可以工作但没有重复行的查询，因为 num 是唯一的：

WITH t AS
(
   SELECT DISTINCT *, ROW_NUMBER() OVER (ORDER BY Date) AS num 
   FROM Original_Import 
   LEFT JOIN eqcas.dbo.BASE_PROXY_VIEW_WITHTARGET ON ADName = Targetuser
   WHERE (BaseProxy = 'agmc' OR ADName = 'agmc')
      AND (Commited IS NULL OR Commited = 0)
)
SELECT DISTINCT ID, num, ADName, Description_User, Description_Amex, Amount, Date
FROM t 
WHERE (t.BaseProxy = 'agmc' OR t.ADName = 'agmc') 
   AND num BETWEEN 0 AND 20
   AND (Commited IS NULL OR Commited = 0)
ORDER BY Date

修复它可能相当简单，但鉴于我不是 SQL Server 人员，我不习惯这些内部查询等。

更新：是的，num 用于分页。

Answer 1

我最近发布的关于ROW_NUMBER() being to SELECT what DENSE_RANK() is to SELECT DISTINCT 的博文似乎晚了两年。您的 CTE 必须替换为：

WITH t AS
(
   SELECT DISTINCT *, DENSE_RANK() OVER (ORDER BY Date, ...) AS num 
   FROM Original_Import 
   LEFT JOIN eqcas.dbo.BASE_PROXY_VIEW_WITHTARGET ON ADName = Targetuser
   WHERE (BaseProxy = 'agmc' OR ADName = 'agmc')
      AND (Commited IS NULL OR Commited = 0)
)
SELECT ...

在上述查询中，DENSE_RANK() 的ORDER BY 子句需要列出来自Original_Import 和BASE_PROXY_VIEW_WITH_TARGET 的所有列，以重现与DISTINCT 关键字相同的顺序。这将为每个重复记录集分配一个等级，这样DISTINCT 将再次起作用。

在referenced blog post 中，我还包含了一个指向SQLFiddle 的链接，用一个更简单的例子来说明这一点。

SELECT DISTINCT
  v, 
  DENSE_RANK() OVER (w) row_number
FROM t
WINDOW w AS (ORDER BY v)
ORDER BY v, row_number

An explanation why DISTINCT removes duplicate rows after window functions having been calculated can be found in this post here.

Answer 2

对此的信心有限，因为我无法测试甚至编译，但这是我所想的一般要点......

WITH t AS
(
   SELECT [insert your fields here], ROW_NUMBER() OVER (ORDER BY Date) AS num 
   FROM (
     SELECT DISTINCT *[insert your fields here]
     FROM Original_Import 
     LEFT JOIN eqcas.dbo.BASE_PROXY_VIEW_WITHTARGET ON ADName = Targetuser
     WHERE (BaseProxy = 'agmc' OR ADName = 'agmc')
      AND (Commited IS NULL OR Commited = 0)) as X
)
SELECT DISTINCT ID, num, ADName, Description_User, Description_Amex, Amount, Date
FROM t 
WHERE (t.BaseProxy = 'agmc' OR t.ADName = 'agmc') 
   AND num BETWEEN 0 AND 20
   AND (Commited IS NULL OR Commited = 0)
ORDER BY Date