如何在同一更新查询中使用另一列新值更新 xml 列节点值？

Question

I want to change the value of 2 columns in one table. One column is varchar and the other is XML. First of all, I want to replace the value of the RECIPIENT column with the new value and replace the node value named as RecipientNo in the XML column with the new value of RecipientNo. How can I do these two operations in the same update function? The query below works. Secondly, DATARECORD table includes too many records. Does modify function take too much time to update the records? If so, how can I increase the performance of modify function or can you suggest another alternative solution? By the way, I cannot add index to DATARECORD table. Thanks.

Here is the sample row;

ID   RECIPIENT   RECORDDETAILS 
1       1         <?xml version="1.0"?>
                  <MetaTag xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
                         xmlns:xsd="http://www.w3.org/XMLSchema"> 
                       <Code>123</Code>
                       <RecipientNo>123</RecipientNo> 
                       <Name>xyz</Name>
                  </MetaTag>'

    CREATE TABLE #TEMPTABLE(
        ID bigint,
        RECIPIENT nvarchar(max),
        RECORDDETAILS xml
        )

    INSERT INTO #TEMPTABLE
    SELECT ID,RECIPIENT,RECORDDETAILS
    FROM DATARECORD WITH (NOLOCK)
    WHERE cast(RECORDDETAILS as varchar(max)) LIKE '%<Code>123</Code>%' and cast(RECORDDETAILS as varchar(max))  LIKE '%MetaTag%' 

    UPDATE #TEMPTABLE SET RECIPIENT = CONCAT('["queryType|1","recipientNoIDENTIFICATION|',RECIPIENT,']')

    UPDATE #TEMPTABLE SET RECORDDETAILS.modify('replace value of (MetaTag/RecipientNo/text())[1] with sql:column("RECIPIENT")')

    UPDATE d
    SET d.RECORDDETAILS =Concat('<?xml version="1.0"?>', CAST(t.RECORDDETAILS AS VARCHAR(max))),
    d.RECIPIENT = t.RECIPIENT
    FROM dbo.DATARECORD as d
    Join #TEMPTABLE as t
    ON t.ID = d.ID

Answer 1

It's certainly possible to update an SQL column and an XML node in the same update statement, eg:

create table DataRecord (
  ID bigint not null primary key,
  Recipient nvarchar(max) not null,
  RecordDetails xml not null
);

insert DataRecord values
  (1, N'1', N'<?xml version="1.0"?>
                  <MetaTag xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
                         xmlns:xsd="http://www.w3.org/XMLSchema"> 
                       <Code>123</Code>
                       <RecipientNo>123</RecipientNo> 
                       <Name>xyz</Name>
                  </MetaTag>');

create table #TempTable (
  ID bigint not null primary key,
  Recipient nvarchar(max) not null,
  RecordDetails xml not null
);

insert #TempTable
  select ID, Recipient, RecordDetails
  from DataRecord with (nolock)
  where cast(RecordDetails as varchar(max)) like '%<Code>123</Code>%' and cast(RecordDetails as varchar(max)) like '%MetaTag%'

-- Change an SQL value and an XML node in the one update statement...
update tt set
  Recipient = NewRecipient,
  RecordDetails.modify('replace value of (/MetaTag/RecipientNo/text())[1] with sql:column("NewRecipient")')
from #TempTable tt
outer apply (
  select NewRecipient = concat('["queryType|1","recipientNoIDENTIFICATION|', Recipient, '"]')
) Calc

select * from #TempTable

Which yields:

ID  Recipient                                       RecordDetails
1   ["queryType|1","recipientNoIDENTIFICATION|1"]   <MetaTag
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:xsd="http://www.w3.org/XMLSchema">
  <Code>123</Code>
  <RecipientNo>["queryType|1","recipientNoIDENTIFICATION|1"]</RecipientNo>
  <Name>xyz</Name>
</MetaTag>

There are a couple of things contributing to your performance problem:

• Converting XML, which SQL Server essentially stores in UTF-16 encoding, to varchar (twice) is expensive. It will also trash any Unicode characters outside your database's collation.
• Performing like matches on the XML (converted to varchar) will be causing TABLE SCAN operations, converting and testing every row in your table.

Some things to consider:

• Add XML Index(es) to the RecordDetails column and use something like WHERE RecordDetails.exists('/MetaTag/Code[.="123"]) to short list the rows to be updated.
• Alternatively, pre-shred your RecordDetails , persist the value of /MetaTag/Code/text() in a table column (eg: MetaTagCode ), and use something like WHERE MetaTagCode='123' in your query. Adding an index to that column will allow SQL to do a much cheaper INDEX SCAN when searching for the desired value instead of a TABLE SCAN.

Since you say you cannot add indexes you're basically going to have to tolerate TABLE SCANs and just wait it out.