Use a LIKE statement on SQL Server XML Datatype

Question

If you have a varchar field you can easily do SELECT * FROM TABLE WHERE ColumnA LIKE '%Test%' to see if that column contains a certain string.

How do you do that for XML Type?

I have the following which returns only rows that have a 'Text' node but I need to search within that node

select * from WebPageContent where data.exist('/PageContent/Text') = 1 

Answer 1

Yet another option is to cast the XML as nvarchar, and then search for the given string as if the XML vas a nvarchar field.

SELECT *  FROM Table WHERE CAST(Column as nvarchar(max)) LIKE '%TEST%' 

I love this solution as it is clean, easy to remember, hard to mess up, and can be used as a part of a where clause.

This might not be the best performing solution, so think twice before deplying it to production. It is however very usefull for a quick debug session, which is where I mostly use it.

EDIT: As Cliff mentions it, you could use:

...nvarchar if there's characters that don't convert to varchar

Answer 2

You should be able to do this quite easily:

SELECT *  FROM WebPageContent  WHERE data.value('(/PageContent/Text)[1]', 'varchar(100)') LIKE 'XYZ%' 

The .value method gives you the actual value, and you can define that to be returned as a VARCHAR(), which you can then check with a LIKE statement.

Mind you, this isn't going to be awfully fast. So if you have certain fields in your XML that you need to inspect a lot, you could:

• create a stored function which gets the XML and returns the value you're looking for as a VARCHAR()
• define a new computed field on your table which calls this function, and make it a PERSISTED column

With this, you'd basically "extract" a certain portion of the XML into a computed field, make it persisted, and then you can search very efficiently on it (heck: you can even INDEX that field!).

Marc