How can I query a value in SQL Server XML column

Question

I have following XML stored in a XML column (called Roles) in a SQL Server database.

<root>
   <role>Alpha</role>
   <role>Beta</role>
   <role>Gamma</role>
</root>

I'd like to list all rows that have a specific role in them. This role passed by parameter.

Answer 1

select
  Roles
from
  MyTable
where
  Roles.value('(/root/role)[1]', 'varchar(max)') like 'StringToSearchFor'

In case your column is not XML, you need to convert it. You can also use other syntax to query certain attributes of your XML data. Here is an example...

Let's suppose that data column has this:

<Utilities.CodeSystems.CodeSystemCodes iid="107" CodeSystem="2" Code="0001F" CodeTags="-19-"..../>

... and you only want the ones where CodeSystem = 2 then your query will be:

select 
  [data] 
from
  [dbo].[CodeSystemCodes_data]
  
where
  CAST([data] as XML).value('(/Utilities.CodeSystems.CodeSystemCodes/@CodeSystem)[1]', 'varchar(max)') = '2'

These pages will show you more about how to query XML in T-SQL:

Querying XML fields using t-sql

Flattening XML Data in SQL Server

EDIT

After playing with it a little bit more, I ended up with this amazing query that uses CROSS APPLY. This one will search every row (role) for the value you put in your like expression...

Given this table structure:

create table MyTable (Roles XML)

insert into MyTable values
('<root>
   <role>Alpha</role>
   <role>Gamma</role>
   <role>Beta</role>
</root>')

We can query it like this:

select * from 

(select 
       pref.value('(text())[1]', 'varchar(32)') as RoleName
from 
       MyTable CROSS APPLY

       Roles.nodes('/root/role') AS Roles(pref)
)  as Result

where RoleName like '%ga%'

You can check the SQL Fiddle here: http://sqlfiddle.com/#!18/dc4d2/1/0