从 XML 文件通过 SQL 读取最大值

Question

My data is stored in a table Transactiontable . I have columns in the table, one of which is PostIT that stores XML data:

enter image description here ---TABLE IMAGE

enter image description here ---XML IMAGE

From the xml file I have to read the max or the most recent transaction datetime.

I am able to read the first node

select 
    convert(xml.Transactiontable).value ('Transaction/DateTime[2]','DATETIME') 
from 
    dbo.transactiontable;

I have to read all the transactional datetime and I should be able to select the max or the latest transaction

I tried cross apply and did not work

select 
    T.N.value ('Transaction/DateTime[2]','DATETIME') 
from
    dbo.transactiontable
cross apply 
    XXX.nodes('TRANSACTION') as T(N)

Answer 1

There are several things to say first:

• Please do not paste your sample data as picture. Nobody wants to type this in.
• Best was, to provide a MCVE or a fiddle with DDL, sample data and your own attempt together with the expected output.
• Always tag as specifically as possible. Tag with your tools and provide vendor and version.

Now to your question:

Again there is something to say first:

• Your XML contains date-time values in a culture dependant format. This is dangerous. some systems will take "01/05/2019" as the first of May, others will read the 5th of January.
• The XML is hard to read. If I get the picture correctly, you have alternating <Datetime> and <TRANSACTION_KEY> elements. It seems to be their sort order to tigh them together. This is a bad design...

Try this as first step:

SELECT dt.value('text()[1]','nvarchar(100)') AS SomeDateTimeValueAsString
FROM YourTable t
CROSS APPLY t.TheXmlColumn.nodes('/DATA/CO/TRANSACTION/DateTime') A(dt);

If this is not enough to get you running, you'll have to invest more effort to your question.