为什么此UPDATE会因唯一的键约束冲突而失败？

我是一个“偶然的” DBA，相对缺乏经验并且对此问题感到困惑。

运行MS SQL Server2012。问题在于此UPDATE语句：

UPDATE dbo.tAccts SET
       Ticket               = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)
FROM dbo.vReclaimable
WHERE OHR_EmpStatus <> 'A'

哪个应该只更新vReclaimable视图返回的tAccts表中的行。

vReclaimable视图基于tAccts表，并返回tAccts中的行的子集。

当我运行它时，它会失败并出现一个唯一的关键错误：

(0 row(s) affected)
Msg 2627, Level 14, State 1, Line 67
Violation of UNIQUE KEY constraint 'UQ__tAccounts_DNIS.Method.Destination.Phones'. Cannot insert duplicate key in object 'dbo.tAccts'. The duplicate key value is (68497, smtp, r00417819@mail.ad.ge.com, 800-905-8793, none).
The statement has been terminated.

公平地说，tAccts表确实具有唯一的键约束：

CONSTRAINT [UQ__tAccounts_DNIS.Method.Destination.Phones] UNIQUE NONCLUSTERED 
(
                [DNIS] ASC,[Method] ASC,[Destination] ASC,[Phone_TF] ASC,[Phone_Local] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) 

但这是奇怪的事情。如果我运行以下两个查询：

select 'tAccts table', dnis, method, destination, phone_tf, phone_local from tAccts where dnis=68497
select 'vReclaimable view', dnis, method, destination, phone_tf, phone_local, daysidle from vReclaimable where dnis=68497

第一个返回两行（按预期）：

(No column name)     dnis   method destination   phone_tf      phone_local
tAccts table  68497  ftp    ftp://faxuser@ap1plm02cige/appliances    800-905-8793  none
tAccts table  68497  unc    \\\\for4as01applge\\cfs_portfolio\\cfs_faxdocs  800-905-8793  none

第二个返回0行（按预期）。

如果“ FROM vReclaimable WHERE OHR_EmpStatus <>'A'”返回0行，为什么UPDATE试图更新DNIS = 68497的行？

（我希望我已经对此进行了充分的描述。我感觉自己缺少明显的东西）

USE [TEST-GEAFax_arley_NEW]
GO

/****** Object:  Table [dbo].[tAccts]    Script Date: 12/9/2015 1:39:41 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[tAccts](
    [Ticket] [varchar](30) NOT NULL,
    [Method] [varchar](15) NOT NULL,
    [AcctOwner] [varchar](15) NOT NULL,
    [DisplayName] [varchar](75) NOT NULL,
    [Destination] [varchar](75) NOT NULL,
    [DNIS] [varchar](20) NOT NULL,
    [DNIS2] [varchar](20) NULL,
    [Phone_TF] [varchar](30) NOT NULL,
    [Phone_Local] [varchar](30) NOT NULL,
    [Phone_PBX] [varchar](255) NOT NULL,
    [UpdatedBy] [varchar](50) NOT NULL,
    [UpdatedOn] [date] NOT NULL,
    [FaxNotes] [varchar](255) NULL,
    [TelcomNotes] [varchar](255) NULL,
    [AcctID] [int] IDENTITY(0,1) NOT NULL,
 CONSTRAINT [PK__tAccounts_AcctID] PRIMARY KEY CLUSTERED 
(
    [AcctID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
 CONSTRAINT [UQ__tAccounts_DNIS.Method.Destination.Phones] UNIQUE NONCLUSTERED 
(
    [DNIS] ASC,
    [Method] ASC,
    [Destination] ASC,
    [Phone_TF] ASC,
    [Phone_Local] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

---------------------------------------------------------------------------------

USE [TEST-GEAFax_arley_NEW]
GO

/****** Object:  View [dbo].[vReclaimable]    Script Date: 12/9/2015 1:39:57 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO


/***********************************************************************
* Written By    : N. Arley Dealey (200018252
* Written On    :
* Updated By    :
* Updated On    :
* Description   : Returns data from tAccts, vRxAl, vWLT_AllGE
* Notes         :
***********************************************************************/
CREATE VIEW [dbo].[vReclaimable] AS
SELECT
        a.Ticket
        , a.Method
        , a.AcctOwner
        , a.DisplayName
        , a.Destination
        , a.DNIS
        , a.DNIS2
        , a.Phone_TF
        , a.Phone_Local
        , a.Phone_PBX
        , a.UpdatedBy
        , a.UpdatedOn
        , a.FaxNotes
        , a.TelcomNotes
        , a.AcctID
        , COUNT(jt.JobID) AS 'FaxesRcvd'
        , CAST(MIN(jt.TimeStamp_UTC) AS DATE) AS 'FirstRcvd'
        , CAST(MAX(jt.TimeStamp_UTC) AS DATE) AS 'LastRcvd'
        , DATEDIFF(dd, MAX(jt.TimeStamp_UTC), GETDATE()) AS 'DaysIdle'
        , o.OHR_EmpSSO
        , o.OHR_EmpStatus
        , o.OHR_EmpName
        , o.OHR_EmpTitle
        , o.OHR_BizIndustryGroup
        , o.OHR_BizSegment
        , o.OHR_BizUnit
        , o.OHR_BizDept
        , o.OHR_BizDomain
FROM
    dbo.tAccts AS a
    LEFT OUTER JOIN dbo.tAccts_Retain AS r ON (a.AcctID = r.AcctID)
    LEFT OUTER JOIN dbo.vWLT_AllGE AS o ON (a.AcctOwner = o.OHR_EmpSSO)
    LEFT OUTER JOIN dbo.vRxAll AS jt ON (a.DNIS = jt.DNIS)
    WHERE ( 1                                               -- place holder, has no effect
            AND r.RetainID IS NULL                          -- out of scope: in Retain table
            AND a.Method = 'smtp'                           -- out of scope: ftp, unc, cifs, printers
            AND a.Phone_Local NOT LIKE '216-%'              -- out of scope: NELA numbers
            AND a.AcctOwner <> 'r00417819'                  -- out of scope: reclaimed numbers
            AND a.AcctOwner <> 'r00336832'                  -- out of scope: never assigned numbers
            AND a.AcctOwner <> 'r00971729'                  -- out of scope: invalid numbers
            AND a.Destination NOT LIKE 'g%@mail.ad.ge.com'  -- out of scope: distribution lists
            AND a.Destination NOT LIKE 'r%@mail.ad.ge.com'  -- out of scope: shared mailboxes
        )
    GROUP BY
        a.DNIS
        -- remaining columns are just for syntax reasons
        , a.Ticket, a.Method, a.AcctOwner, a.DisplayName, a.Destination, a.DNIS2, a.Phone_TF, a.Phone_Local, a.Phone_PBX, a.UpdatedBy, a.UpdatedOn, a.FaxNotes, a.TelcomNotes, a.AcctID
        , o.OHR_EmpSSO, o.OHR_EmpStatus, o.OHR_EmpName, o.OHR_EmpTitle
        , o.OHR_BizIndustryGroup, o.OHR_BizSegment, o.OHR_BizUnit, o.OHR_BizDept, o.OHR_BizDomain

GO

归结为UPDATE语句的作用。这并不完全明显，但是您的陈述与此等效：

UPDATE upd SET
         Ticket             = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)
FROM 
    dbo.tAccts AS upd 
  CROSS JOIN
    dbo.vReclaimable AS v
WHERE OHR_EmpStatus <> 'A' ;

由于没有在dbo.tAccts表中提及该表，FROM并且在表和视图之间没有联接，或者在表和视图之间没有条件，因此会导致CROSS联接并尝试更新表的所​​有行（而不仅仅是从视图中），并且可能会更新时代也是如此！

您可以使用以下方法添加联接（或在何处）条件：

UPDATE upd SET
         Ticket             = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)
FROM 
    dbo.tAccts AS upd 
  JOIN
    dbo.vReclaimable AS v
      ON v.PK = upd.PK              -- whatever the PK column is
WHERE OHR_EmpStatus <> 'A' ;

或（使用您的版本）：

UPDATE dbo.tAccts SET
       Ticket               = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)
FROM dbo.vReclaimable
WHERE OHR_EmpStatus <> 'A'
  AND vReclaimable.PK = tAccts.PK ;

或者，您可以（可能）简单地更新视图。为此，视图必须符合有关“可更新视图”的限制。请参阅MSDN文档中的相关段落：CREATE VIEW，可更新视图：

UPDATE dbo.vReclaimable SET
       Ticket               = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)

WHERE OHR_EmpStatus <> 'A' ;

似乎您的更新查询中的表之间没有联接。

UPDATE dbo.tAccts SET
       Ticket               = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)
FROM dbo.vReclaimable
WHERE OHR_EmpStatus <> 'A'

这里必须有一些东西可以匹配表之间的行，例如tAccts.id = vReclaimable.id

另一种放置方式：

问题是您认为语句“应该仅更新tAccts表中由vReclaimable视图返回的行”。

事实并非如此。它将更新tAccts（紧随其后的表中UPDATE）与OHR_EmpStatus <> 'A'（条件中的WHERE）匹配的所有行。vReclaimable这样做可能会使用其中的数据（但是您不会对其进行任何引用）。

如果您希望将其限制为中的行，vReclaimable除了提供的其他选项外，还可以使用子查询：

UPDATE dbo.tAccts SET
       Ticket               = 'ARP.ExGE'
       , Method             = 'smtp'
       , AcctOwner          = 'r00417819'
       , DisplayName = '~AppLight HBSFax-Inactive'
       , Destination = 'r00417819@mail.ad.ge.com'
       , UpdatedBy          = SYSTEM_USER
       , UpdatedOn          = CAST(GetDate() AS DATE)
WHERE OHR_EmpStatus <> 'A' AND tAccts.key IN (SELECT key FROM vReclaimable)

如果以下查询返回多行：

select 'tAccts table', dnis, method, destination, phone_tf, phone_local 
from tAccts
where OHR_EmpStatus <> 'A'

那么您将尝试使用相同的值更新多行，从而违反了唯一约束。

另一个选择是：您不需要

来自dbo.vReclaimable

因为您没有在更新语句中使用此表中的任何值。