XQuery sql Join 在 join 不匹配时插入空节点

Question

我正在使用 SQL Server 2012，我正在寻找一种方法来更新我的 xml 列，方法是从另一个 table.

中查找值

我有以下架构：

USE tempdb;
GO

DROP TABLE IF EXISTS [dbo].[tblstepid];

CREATE TABLE [dbo].[tblstepid](
    [stepid] [uniqueidentifier]  NOT NULL,
    [name] nvarchar(32) NOT NULL
);

INSERT INTO dbo.tblstepid ([stepid], name ) VALUES ('E36A3450-1C8F-44DA-B4D0-58E5BFE2A987','step1')

INSERT INTO dbo.tblstepid ([stepid], name ) VALUES ('11D70A50-08AC-4767-A0D3-87717384FF45','step2')

DROP TABLE IF EXISTS [dbo].[tblStepList];

CREATE TABLE [dbo].[tblStepList](
    [ToDoId] [int] IDENTITY(1,1) NOT NULL,
    [Data] [xml] NOT NULL
);

INSERT INTO dbo.tblStepList ([Data]) VALUES
(N'<Steplist>
  <Step>
    <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>     
  </Step>
  <Step>
    <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
    <TextReadingId>12</TextReadingId>

  </Step>
</Steplist>');





    INSERT INTO dbo.tblStepList ([Data]) VALUES
(N'<Steplist>
  <Step>
    <StepId>d9e42387-56e3-40a1-9698-e89c930d98d1</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>   
    <TextReadingId>0</TextReadingId>  
  </Step>
  <Step>
    <StepId>e5eaf947-24e1-4d3b-a92a-d6a90841293b</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
  </Step>
</Steplist>')

现在我想在另一个 table 中更新所有具有匹配步骤 ID 的步骤，如下所示：

UPDATE sl
SET Data = (
    SELECT v.Step.query('
<Step>{./*,    
            <stepname>{sql:column("sr.name")}</stepname>
        }
</Step>
    ')
    FROM sl.Data.nodes('/Steplist/Step') v(Step)
     left JOIN tblStepID sr ON sr.StepId = v.Step.value('(StepId/text())[1]','uniqueidentifier')
    FOR XML PATH(''), ROOT('Steplist'), TYPE
)
FROM tblStepList sl;

我的结果 xml 输出有一个我不想要的空节点。我如何编写我的连接不为我添加空节点并且如果没有匹配项也不设置数据这意味着我的 table xml 中的第二条记录永远不会被触及？

我要解决的问题是，我正在尝试通过从另一个 table 加入来为具有数百万条记录的 table 更新 xml，但我不想如果连接不匹配，更新语句触及数据。

<Steplist>
  <Step>
    <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>
    <stepname>step1</stepname>
  </Step>
  <Step>
    <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
    <TextReadingId>12</TextReadingId>
    <stepname />
  </Step>
</Steplist>

我的预期输出如下：

<Steplist>
  <Step>
    <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>
    <stepname>step1</stepname>
  </Step>
  <Step>
    <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
    <TextReadingId>12</TextReadingId>
  </Step>
</Steplist>

Answer 1

请尝试以下解决方案。

我添加了几个 XQuery if/else 语句来防止出现空的 <stepname /> 标记。

SQL

USE tempdb;
GO

-- DDL and sample data population, start
DROP TABLE IF EXISTS [dbo].[tblStepID];
DROP TABLE IF EXISTS [dbo].[tblStepList];

CREATE TABLE dbo.tblstepid(
    stepid uniqueidentifier  NOT NULL,
    [name] nvarchar(32) NOT NULL
);
INSERT INTO dbo.tblStepID (StepId, [Name]) VALUES
('e36a3450-1c8f-44da-b4d0-58e5bfe2a987', 'step1'),
('4078c1b1-71ea-4578-ba61-d2f6a5126ba1', 'step2');

CREATE TABLE [dbo].[tblStepList](
    [ToDoId] [int] IDENTITY(1,1) NOT NULL,
    [Data] [xml] NOT NULL
);

INSERT INTO dbo.tblStepList ([Data]) VALUES
(N'<Steplist>
  <Step>
    <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>     
  </Step>
  <Step>
    <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
    <TextReadingId>12</TextReadingId>
  </Step>
</Steplist>'),
(N'<Steplist>
  <Step>
    <StepId>d9e42387-56e3-40a1-9698-e89c930d98d1</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>   
    <TextReadingId>0</TextReadingId>  
  </Step>
  <Step>
    <StepId>e5eaf947-24e1-4d3b-a92a-d6a90841293b</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
  </Step>
</Steplist>');
-- DDL and sample data population, end

UPDATE sl
SET Data = (
    SELECT v.Step.query('
    <Step>{./*,   
            if (not(./stepname)) then 
                if (not(empty(sql:column("sr.name")))) then <stepname>{sql:column("sr.name")}</stepname>
                else ()
            else ()
        }
    </Step>
')
FROM sl.Data.nodes('/Steplist/Step') AS v(Step)
LEFT JOIN tblStepID sr ON sr.StepId = v.Step.value('(StepId/text())[1]','uniqueidentifier')
FOR XML PATH(''), ROOT('Steplist'), TYPE
)
FROM tblStepList AS sl;

-- test
SELECT * FROM dbo.tblStepList;

XQuery sql Join 在 join 不匹配时插入空节点

XQuery sql Join inserts empty node when join does not match

sql-server

xml

tsql

xquery

xquery-sql