SQL Server - 子选择返回超过 1 行。如何正确选择全部？

【问题标题】：SQL Server - Subselect returns more than 1 row. How to properly select all?SQL Server - 子选择返回超过 1 行。如何正确选择全部？
【发布时间】：2019-02-27 15:30:12
【问题描述】：

与这个问题相关的是表格“tAttributes”

CREATE TABLE [dbo].[tAttributes](
    [GUID] [uniqueidentifier] ROWGUIDCOL  NOT NULL,
    [Attribute] [varchar](50) NOT NULL,
    [RelatedGUID] [uniqueidentifier] NULL,
    [LevelLow] [decimal](12, 2) NULL,
    [LevelHigh] [decimal](12, 2) NULL,
    [LevelStep] [decimal](12, 2) NULL,
    [AttributeLevel] [decimal](12, 2) NULL,
    [Description] [varchar](100) NULL,
    [AutoselectGUID] [uniqueidentifier] NULL,
    [CompanySystem] [bit] NOT NULL,
    [PeopleSystem] [bit] NOT NULL,
    [SearchSystem] [bit] NOT NULL,
    [Populate] [bit] NOT NULL,
    [Synonyms] [varchar](255) NULL,
    [TimeEntered] [datetime] NULL,
    [UserEnteredGUID] [uniqueidentifier] NULL,
    [TimeUpdated] [datetime] NULL,
    [UserUpdatedGUID] [uniqueidentifier] NULL,
    [UpdateHistory] [varchar](255) NULL,
    [Stamp] [timestamp] NULL,
 CONSTRAINT [PK_tAttributes] PRIMARY KEY CLUSTERED 
(
    [GUID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON, FILLFACTOR = 90) ON [PRIMARY],
 CONSTRAINT [IX_AttributeRelatedGUID] UNIQUE NONCLUSTERED 
(
    [Attribute] ASC,
    [RelatedGUID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON, FILLFACTOR = 90) ON [PRIMARY]
) ON [PRIMARY]

它有属性例如：

GUID|Attribute|RelatedGUID|....
1   | Val1    | 2         |
3   | Val2    | NULL      |
4   | val3    | 5         |

Val1 是一个属性，Val2 其中 RelatedGUID 为 NULL 是一个类别

活生生的例子，即：

F0F9EA32-C3AC-48A9-B6BE-09807B720818| gaming | 09E898CC-5DE2-4664-B9B2-14F17FBC37DB
32B74398-83C9-4225-81E2-0A1CB6C67954 | Function skills | NULL

“游戏”是一个属性

“功能技能”是一个类别

我如何对其进行子选择，以便在“属性”列中，我将只有属性、RelatedGUID 与 NULL 不同的值，而在“类别”、类别、具有相关GUID 等于 NULL 的值列中？

我有这个问题：

select tsearch.Description,

tcompany.CompanyName,
tcompany.GUID as CompanyGuid,
tcompanylocation.LocationName,
tsearchtype.SearchType,
tsearchresult.searchresult,
tpeople.GUID as PersonPlacedGuid,
tpeople.LastName As PersonPlacedLName,
tpeople.Firstname As PersonPlacedFName,
tsearch.SearchNotes,
( select tpeople.Firstname  from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as repfirstname, 
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as replastname,
tsearch.RepresentativeGUID as RepGuid,
tposition.Position as backgroundposition,
tdepartment.Department as backgrounddepartment,
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
tsearch.ReferredByGUID as PersonwhorefferedGuid,
( select tcompany.CompanyName from tCompany where tCompany.guid=tSearch.PlacedFromGUID) as placedfrom,
tinstantstatustype.InstantStatus,
tWorkbench.WorkbenchName,
( select tpeople.Lastname from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as Candlastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as candFirstname,
tInstantStatus.ForClientNotes,
tinstantstatus.InstantStatusNotes as InstanttatusNotesSummary,
( select top 1 tAttributes.Attribute from tAttributes where tAttributes.RelatedGUID is not NUll ) as Attributes,
( select top 1 tAttributes.Attribute from tAttributes where tAttributes.RelatedGUID is  NUll ) as Categories


from tSearch


full join tCompany on tsearch.CompanyGUID = tcompany.guid
full join tcompanylocation on tcompanylocation.guid= tcompany.LocationGUID
full join tSearchType on tsearchtype.GUID = tSearch.SearchTypeGUID
full join tSearchResult on tSearchResult.GUID = tsearch.SearchResultGUID
full join tPeople on tPeople.GUID = tsearch.PlacedGUID
full join tPosition on tPosition.GUID = tsearch.PositionGUID
full join tDepartment on tdepartment.GUID = tsearch.DepartmentGUID
full join tInstantStatus on tInstantStatus.SearchGUID = tSearch.guid
full join tInstantStatusType on tInstantStatusType.GUID = tInstantStatus.InstantStatusGUID 
full join tWorkbench on tWorkbench.SearchGUID=tsearch.GUID
full join tSearchCluendex on tSearchCluendex.CPSGUID=tsearch.GUID
full join tAttributes on tAttributes.GUID=tSearchCluendex.AttributeGUID

这里我使用了“top 1”技巧，但问题是类别多于 1，因此“top 1”不是完整的解决方案：

( select top 1 tAttributes.Attribute from tAttributes where tAttributes.RelatedGUID is not NUll ) as Attributes,
( select top 1 tAttributes.Attribute from tAttributes where tAttributes.RelatedGUID is  NUll ) as Categories

提前致谢！

更新 1

基于@Shungo 提示。

这也不起作用：

select tsearch.Description,

tcompany.CompanyName,
tcompany.GUID as CompanyGuid,
tcompanylocation.LocationName,
tsearchtype.SearchType,
tsearchresult.searchresult,
tpeople.GUID as PersonPlacedGuid,
tpeople.LastName As PersonPlacedLName,
tpeople.Firstname As PersonPlacedFName,
tsearch.SearchNotes,
( select tpeople.Firstname  from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as repfirstname, 
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as replastname,
tsearch.RepresentativeGUID as RepGuid,
tposition.Position as backgroundposition,
tdepartment.Department as backgrounddepartment,
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
tsearch.ReferredByGUID as PersonwhorefferedGuid,
( select tcompany.CompanyName from tCompany where tCompany.guid=tSearch.PlacedFromGUID) as placedfrom,
tinstantstatustype.InstantStatus,
tWorkbench.WorkbenchName,
( select tpeople.Lastname from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as Candlastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as candFirstname,
tInstantStatus.ForClientNotes,
tinstantstatus.InstantStatusNotes as InstanttatusNotesSummary,
( select a1.Attribute from tAttributes where tAttributes.RelatedGUID is not NUll ) as Attributes,
( select a1.Attribute from tAttributes where tAttributes.RelatedGUID is  NUll ) as Categories


from tSearch


full join tCompany on tsearch.CompanyGUID = tcompany.guid
full join tcompanylocation on tcompanylocation.guid= tcompany.LocationGUID
full join tSearchType on tsearchtype.GUID = tSearch.SearchTypeGUID
full join tSearchResult on tSearchResult.GUID = tsearch.SearchResultGUID
full join tPeople on tPeople.GUID = tsearch.PlacedGUID
full join tPosition on tPosition.GUID = tsearch.PositionGUID
full join tDepartment on tdepartment.GUID = tsearch.DepartmentGUID
full join tInstantStatus on tInstantStatus.SearchGUID = tSearch.guid
full join tInstantStatusType on tInstantStatusType.GUID = tInstantStatus.InstantStatusGUID 
full join tWorkbench on tWorkbench.SearchGUID=tsearch.GUID
full join tSearchCluendex on tSearchCluendex.CPSGUID=tsearch.GUID
full join tAttributes on tAttributes.GUID=tSearchCluendex.AttributeGUID
LEFT JOIN tAttributes AS a1 ON a1.GUID=tSearchCluendex.AttributeGUID

返回：

Msg 512, Level 16, State 1, Line 3
Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

更新 2：

看起来更好，不幸的是属性和类别具有相同的值。我希望属性具有相关GUID 不为NULL 的值和相关GUID 的值为NULL 的类别。

如何指定这个条件？

select tsearch.Description,

tcompany.CompanyName,
tcompany.GUID as CompanyGuid,
tcompanylocation.LocationName,
tsearchtype.SearchType,
tsearchresult.searchresult,
tpeople.GUID as PersonPlacedGuid,
tpeople.LastName As PersonPlacedLName,
tpeople.Firstname As PersonPlacedFName,
tsearch.SearchNotes,
( select tpeople.Firstname  from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as repfirstname, 
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as replastname,
tsearch.RepresentativeGUID as RepGuid,
tposition.Position as backgroundposition,
tdepartment.Department as backgrounddepartment,
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
tsearch.ReferredByGUID as PersonwhorefferedGuid,
( select tcompany.CompanyName from tCompany where tCompany.guid=tSearch.PlacedFromGUID) as placedfrom,
tinstantstatustype.InstantStatus,
tWorkbench.WorkbenchName,
( select tpeople.Lastname from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as Candlastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as candFirstname,
tInstantStatus.ForClientNotes,
tinstantstatus.InstantStatusNotes as InstanttatusNotesSummary,
tAttributes.Attribute as Attributes,
a1.Attribute as Categories


from tSearch


full join tCompany on tsearch.CompanyGUID = tcompany.guid
full join tcompanylocation on tcompanylocation.guid= tcompany.LocationGUID
full join tSearchType on tsearchtype.GUID = tSearch.SearchTypeGUID
full join tSearchResult on tSearchResult.GUID = tsearch.SearchResultGUID
full join tPeople on tPeople.GUID = tsearch.PlacedGUID
full join tPosition on tPosition.GUID = tsearch.PositionGUID
full join tDepartment on tdepartment.GUID = tsearch.DepartmentGUID
full join tInstantStatus on tInstantStatus.SearchGUID = tSearch.guid
full join tInstantStatusType on tInstantStatusType.GUID = tInstantStatus.InstantStatusGUID 
full join tWorkbench on tWorkbench.SearchGUID=tsearch.GUID
full join tSearchCluendex on tSearchCluendex.CPSGUID=tsearch.GUID
full join tAttributes on tAttributes.GUID=tSearchCluendex.AttributeGUID
LEFT JOIN tAttributes AS a1 ON a1.GUID=tSearchCluendex.AttributeGUID

更新 3：

select * from tAttributes where RelatedGUID is null;

列出 11 个类别，RelatedGUID 为 NULL 的条目。

现在当我按照@iamdave 解决方案的建议尝试时：

select tsearch.Description,

tcompany.CompanyName,
tcompany.GUID as CompanyGuid,
tcompanylocation.LocationName,
tsearchtype.SearchType,
tsearchresult.searchresult,
tpeople.GUID as PersonPlacedGuid,
tpeople.LastName As PersonPlacedLName,
tpeople.Firstname As PersonPlacedFName,
tsearch.SearchNotes,
( select tpeople.Firstname  from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as repfirstname, 
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.RepresentativeGUID) as replastname,
tsearch.RepresentativeGUID as RepGuid,
tposition.Position as backgroundposition,
tdepartment.Department as backgrounddepartment,
( select tpeople.Lastname from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tSearch.ReferredByGUID) as referredbylastname,
tsearch.ReferredByGUID as PersonwhorefferedGuid,
( select tcompany.CompanyName from tCompany where tCompany.guid=tSearch.PlacedFromGUID) as placedfrom,
tinstantstatustype.InstantStatus,
tWorkbench.WorkbenchName,
( select tpeople.Lastname from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as Candlastname,
( select tpeople.FirstName from tpeople where tpeople.guid=tInstantStatus.PeopleGUID) as candFirstname,
tInstantStatus.ForClientNotes,
tinstantstatus.InstantStatusNotes as InstanttatusNotesSummary,
a1.Attribute as Attributes,
a2.Attribute as Categories


from tSearch


full join tCompany on tsearch.CompanyGUID = tcompany.guid
full join tcompanylocation on tcompanylocation.guid= tcompany.LocationGUID
full join tSearchType on tsearchtype.GUID = tSearch.SearchTypeGUID
full join tSearchResult on tSearchResult.GUID = tsearch.SearchResultGUID
full join tPeople on tPeople.GUID = tsearch.PlacedGUID
full join tPosition on tPosition.GUID = tsearch.PositionGUID
full join tDepartment on tdepartment.GUID = tsearch.DepartmentGUID
full join tInstantStatus on tInstantStatus.SearchGUID = tSearch.guid
full join tInstantStatusType on tInstantStatusType.GUID = tInstantStatus.InstantStatusGUID 
full join tWorkbench on tWorkbench.SearchGUID=tsearch.GUID
full join tSearchCluendex on tSearchCluendex.CPSGUID=tsearch.GUID 
full join tAttributes AS a1 ON a1.GUID=tSearchCluendex.AttributeGUID and a1.RelatedGUID is not NULL
full join tAttributes AS a2 ON a2.GUID=tSearchCluendex.AttributeGUID and a2.RelatedGUID is NULL

它返回如下输出：

即

...    Attribute  |  Category

...    NULL       |  NULL
...    Programmer |  NULL
...    Secretary  |  NULL
...    Manager    |  NULL

“程序员”应该在“IT”类别中，“秘书”在“Biz Dev”等中。所以属性没问题，但没有查找类别，尽管存在 JOIN 和条件 ....

这个数据库很大，大约有 40 个表，所以我很难粘贴 SQL 结构，但希望一些聪明而善良的人能明白这一点。如果没有，请告诉我应该粘贴什么（请指定要在 MS SSMS 中执行的命令）

谢谢，

【问题讨论】：

  • 如果您希望得到多个结果，您必须为此使用JOIN。但是你会得到重复的行...
  • 重复行是可以的，只要我有相互匹配的属性和类别列。怎么做？谢谢！
  • 什么是tAttributes.RelatedGUID？如果它指向结果集的 GUID，只需添加 LEFT JOIN 并在 ON-clause 中使用此值
  • 另一个提示：如果您在连接中更频繁地使用同一个表，则必须使用名称别名。有人认为像LEFT JOIN tAttributes AS a1 ON a1.RelatedGUID=Someother.GUID。在您的选择列表中，您将获得a1.Attribute 的值。下一次调用“a2”等等...
  • @android_dev，尝试将您的( select a1.Attribute .... 替换为at.Attribute。那里不需要子选择...

标签： sql-server tsql


【解决方案1】：

CASE 语句应该可以解决问题。我们的想法是检查每条记录中的值并相应地继续，而不是寻找 null 或非 null 的记录。比如：

SELECT
(CASE WHEN tAttributes.RelatedGUID is not null then tAttributes.Attribute ELSE null END) as Attributes,
(CASE WHEN tAttributes.RelatedGUID is null then tAttributes.Attribute ELSE null END) as Categories
FROM tAttributes

【讨论】：

  • 谢谢！！！好主意....我正在检查我的数据集，但它似乎正在做它应该做的事情
【解决方案2】：

在 where 和 using CASE .. WHEN .. THEN.. 尝试以下方式添加条件..

select col1,col2,...colN..from Table where clm1 = CASE WHEN @PARAMETER = 0 THEN COL1 ELSE @PARAMETER

一旦您在 WHERE 条件中设置了相同的列名，然后如果您想作为参数传递，则从表中检索所有数据，然后根据表中的条件值检索。

【讨论】：

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