T-SQL 查询在紧接着运行时返回不同数量的行

下午所有

奇怪的是这个。我编写了一个相当简单的查询，并且我认为它工作正常。但是，当我一次又一次地多次运行查询时，每次都会得到不同的行数。它是一个实时数据库，但除了我之外，今天没有人使用它。我在参数中设置的日期范围是过去的日期，因此新的\已删除的记录不应影响它。所以我有点困惑为什么有时我会得到更多的行，有时会更少的行，而我每次都应该返回相同的行。复制下面的代码

DECLARE 
        @From date,
        @To date

SET @From = '01/07/2015'
SET @To = '31/12/2015'

--AS


SELECT DISTINCT
    BR.Branch, 
    DIV.Division,
    BCM.ClientRef@ AS 'Client Reference',
    BPY.PolicyRef@ AS 'Policy Reference',
    AE.Name AS 'Account Executive',
    DIV2.#Name AS 'Account Handler',
    BTX.Dt_raised AS 'Effective Date',
    BTX.Ledger_dt AS 'Ledger Date',
    INS.VTDescription AS 'Insurer',
    BPY.Ptype AS 'Policy Type',
    BTX.Orig_Debt AS 'GWP',
    COALESCE(BTX.Comm_amt, 0) AS 'Commission',
    CASE
        WHEN BTX.Ccode = '7' THEN 0
        ELSE COALESCE(CHG.Orig_Debt, 0)
    END AS 'Fee',
    COALESCE(BTX.Comm_amt, 0) + CASE WHEN BTX.Ccode = '7' THEN 0 ELSE COALESCE(CHG.Orig_Debt, 0) END AS 'Income',
    CASE DATENAME(MONTH, BTX.Dt_Raised)
        WHEN 'July' THEN YEAR(BTX.Dt_Raised)
        WHEN 'August' THEN YEAR(BTX.Dt_Raised)
        WHEN 'September' THEN YEAR(BTX.Dt_Raised)
        WHEN 'October' THEN YEAR(BTX.Dt_Raised)
        WHEN 'November' THEN YEAR(BTX.Dt_Raised)
        WHEN 'December' THEN YEAR(BTX.Dt_Raised)
        WHEN 'January' THEN YEAR(DATEADD(YEAR, -1, BTX.Dt_Raised))
        WHEN 'February' THEN YEAR(DATEADD(YEAR, -1, BTX.Dt_Raised))
        WHEN 'March' THEN YEAR(DATEADD(YEAR, -1, BTX.Dt_Raised))
        WHEN 'April' THEN YEAR(DATEADD(YEAR, -1, BTX.Dt_Raised))
        WHEN 'May' THEN YEAR(DATEADD(YEAR, -1, BTX.Dt_Raised))
        WHEN 'June' THEN YEAR(DATEADD(YEAR, -1, BTX.Dt_Raised))
    END AS 'FinYear',
    CASE DATENAME(MONTH, BTX.Dt_Raised)
        WHEN 'January' THEN 'Ja'
        WHEN 'February' THEN 'Fe'
        WHEN 'March' THEN 'Ma'
        WHEN 'April' THEN 'Ap'
        WHEN 'May' THEN 'My'
        WHEN 'June' THEN 'Ju'
        WHEN 'July' THEN 'Jy'
        WHEN 'August' THEN 'Au'
        WHEN 'September' THEN 'Se'
        WHEN 'October' THEN 'Oc'
        WHEN 'November' THEN 'No'
        WHEN 'December' THEN 'De'
    END AS 'Month Letter',
    DATENAME(MONTH, BTX.Dt_Raised) AS 'MonthName',
    CASE DATENAME(MONTH, BTX.Dt_Raised)
        WHEN 'January' THEN 7
        WHEN 'February' THEN 8
        WHEN 'March' THEN 9
        WHEN 'April' THEN 10
        WHEN 'May' THEN 11
        WHEN 'June' THEN 12
        WHEN 'July' THEN 1
        WHEN 'August' THEN 2
        WHEN 'September' THEN 3
        WHEN 'October' THEN 4
        WHEN 'November' THEN 5
        WHEN 'December' THEN 6
    END AS 'Order',
    CASE ROW_NUMBER() OVER (PARTITION BY BCM.ClientRef@ ORDER BY BCM.ClientRef@)
        WHEN 1 THEN 1 ELSE 0
    END AS 'Client Count', 
    CASE ROW_NUMBER() OVER (PARTITION BY BPY.PolicyRef@ ORDER BY BPY.PolicyRef@)
        WHEN 1 THEN 1 ELSE 0
    END AS 'Policy Count'
FROM icp_yyclient AS BCM 
INNER JOIN icp_brpolicy AS BPY ON BCM.ClientRef@ = BPY.ClientRef@ AND BCM.Branch@ = BPY.Branch@
INNER JOIN icp_brcledger AS BTX ON BPY.PolicyRef@ = BTX.PolicyRef@ AND BPY.Branch@ = BTX.Branch@
LEFT JOIN icp_brcledger AS CHG ON BTX.Chg_ptr = CHG.Suffix AND BTX.PolicyRef@ = CHG.PolicyRef@ AND BTX.Branch@ = CHG.Branch@
LEFT JOIN AccountExecutives AS AE ON BCM.Job1 = AE.Code
LEFT JOIN icp_bredetail AS DIV2 ON BPY.#Exec = DIV2.Code AND BPY.Branch@ = DIV2.Branch@
LEFT JOIN Division_VT AS DIV ON DIV2.Ext_department = DIV.Division
LEFT JOIN Branch_VT AS BR ON DIV.Branch = BR.VTId
LEFT JOIN icp_INSC_VT AS INS ON BPY.Insco_INSC_VTId = INS.VTId

WHERE
    BPY.Branch@ = 0
    AND BTX.Dt_Raised BETWEEN @From AND @To
    AND (BTX.Trantype IN ('New Business') AND BTX.Trantype <> 'Charge')
    AND (BPY.Term_code IS NULL AND BPY.Term_date IS NULL)
ORDER BY BR.Branch, DIV.Division, BCM.ClientRef@

这是一个简单的例子，说明了如何ROW_NUMBER()查询会影响结果的数量：

declare @t table (a int, b int, c int)
insert into @t(a,b,c) values
(1,1,1),
(1,1,1),
(1,1,2)

select distinct a,c,CASE ROW_NUMBER() OVER (ORDER BY b) WHEN 1 THEN 1 ELSE 0 END
from @t

你会注意到我的ORDER BY子句是不足的了解哪些行将被分配哪些行号。运行这个查询，我通常会得到：

a           c           
----------- ----------- -----------
1           1           0
1           1           1
1           2           0

然而，this结果集也是可能的：

a           c           
----------- ----------- -----------
1           1           0
1           2           1

这仅取决于哪一行被分配行号 1。

如果您想要确定性，请确保在您的PARTITION and ORDER BY条款，以便您know每行分配的行号将被唯一确定。