How to query xml column in tsql

Question

I have a table, T1, with a XML column, EventXML, on SQL Server 2008. I want to query all the rows where certain node contains a particular value. Better, I'd like to retrieve the value in a different node. The table T1:

T1:
   EventID, int
   EventTime, datetime
   EventXML, XML

Here is an example XML hierarchy:

<Event>
   <Indicator>
      <Name>GDP</Name>
   </Indicator>
   <Announcement>
      <Value>2.0</Value>
      <Date>2012-01-01</Date>
   </Announcement>
</Event>

1. How to find all the rows related to "GDP" Indicator;
2. How to get all values for "GDP" Indicator;

Solution 1

How about this?

SELECT 
    EventID, EventTime,
    AnnouncementValue = t1.EventXML.value('(/Event/Announcement/Value)[1]', 'decimal(10,2)'),
    AnnouncementDate = t1.EventXML.value('(/Event/Announcement/Date)[1]', 'date')
FROM
    dbo.T1
WHERE
    t1.EventXML.exist('/Event/Indicator/Name[text() = "GDP"]') = 1

It will find all rows where the /Event/Indicator/Name equals GDP and then it will display the <Announcement>/<Value> and <Announcement>/<Date> for those rows.

See SQLFiddle demo

Solution 2

DECLARE @t XML = '
<Event>
   <Indicator>
      <Name>GDP</Name>
   </Indicator>
   <Announcement>
      <Value>2.0</Value>
      <Date>2012-01-01</Date>
   </Announcement>
</Event>
<Event>
   <Indicator>
      <Name>Other</Name>
   </Indicator>
   <Announcement>
      <Value>3.0</Value>
      <Date>2012-01-01</Date>
   </Announcement>
</Event>
'

SELECT  node.value('.', 'NUMERIC(20, 2)')
FROM    @t.nodes('/Event[Indicator/Name/node()=''GDP'']/Announcement/Value') t(node)