为什么此更新在唯一的键约束冲突中失败？

Question

我是一个“偶然”的DBA，相对缺乏经验，对这个问题感到困惑。

运行MS SQL Server 2012。问题在于这个更新语句：

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'

它应该只更新tAccts表中由vReclaimable视图返回的行。

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

当我运行它时，它会失败，只有一个唯一的键错误：

(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表确实有一个唯一的键约束：

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) 

但奇怪的是。如果我运行这两个查询：

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(如预期的那样)：

(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(如预期的那样)。

如果“FROM vReclaimable WHERE OHR_EmpStatus <>‘A”返回0行，为什么更新试图更新DNIS=68497所在的行？

(我希望我对此有充分的描述。我有种感觉，我错过了一些显而易见的东西)

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

Answer 1

它归结为UPDATE语句所做的工作。这并不是完全显而易见的，但你的陈述相当于这句话：

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' ;

由于在dbo.tAccts中没有提到FROM表，也没有join或表与视图之间的条件，所以它会导致CROSS连接并尝试更新表的所有行(而不仅仅是从视图)，而且可能也会多次更新！

可以使用以下方法添加联接(或位置)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' ;

或者(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。要使此操作正常，视图必须符合“可更新视图”的限制。请参阅MSDN文档中的相关段落：CREATE VIEW，Updatable Views：

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' ;

Answer 2

似乎在update查询中的表之间没有连接。

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'

在这里，必须在表之间匹配行，例如tAccts.id = vReclaimable.id

Answer 3

另一种说法是：

问题在于您认为语句“应该只更新tAccts表中由vReclaimable视图返回的行”。

事实并非如此。它更新tAccts (UPDATE后面提到的表)中与OHR_EmpStatus <> 'A' (WHERE中的条件)匹配的所有行。在这样做时，它可能使用来自vReclaimable的数据(但您没有引用它)。

如果要将其限制为vReclaimable中的行，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)