Querying XML tag in SQL server

Question

I have a table Student with a column studentStateinfo which consist of XML value as below.

<params xmlns="">
  <OldStudentID>1aedghe1d8ef</OldStudentID>
</params>

Now when I query this table Student I only want to check whether studentStateinfo column have an XML data with tag <OldStudentID>

Answer 1

Use the exist() Method (xml Data Type)

Example using a variable, you should change that to a column instead.

declare @X xml = '
<params xmlns="">
  <OldStudentID>1aedghe1d8ef</OldStudentID>
</params>';

select @X.exist('/params/OldStudentID');