Functions on String Values - contains
Applies to: 
SQL Server
Returns a value of type xs:boolean indicating whether the value of $arg1 contains a string value specified by $arg2.
Syntax
fn:contains ($arg1 as xs:string?, $arg2 as xs:string?) as xs:boolean?
Arguments
$arg1
String value to test.
$arg2
Substring to look for.
Remarks
If the value of $arg2 is a zero-length string, the function returns True. If the value of $arg1 is a zero-length string and the value of $arg2 is not a zero-length string, the function returns False.
If the value of $arg1 or $arg2 is the empty sequence, the argument is treated as the zero-length string.
The contains() function uses XQuery's default Unicode code point collation for the string comparison.
The substring value specified for $arg2 has to be less than or equal to 4000 characters. If the value specified is greater than 4000 characters, a dynamic error condition occurs and the contains() function returns an empty sequence instead of a Boolean value of True or False. SQL Server does not raise dynamic errors on XQuery expressions.
In order to get case-insensitive comparisons, the upper-case or lower-case functions can be used.
Supplementary Characters (Surrogate Pairs)
The behavior of surrogate pairs in XQuery functions depends on the database compatibility level and, in some cases, on the default namespace URI for functions. For more information, see the section "XQuery Functions Are Surrogate-Aware" in the topic Breaking Changes to Database Engine Features in SQL Server 2016. Also see ALTER DATABASE Compatibility Level (Transact-SQL) and Collation and Unicode Support.
Examples
This topic provides XQuery examples against XML instances stored in various xml-type columns in the AdventureWorks database.
A. Using the contains() XQuery function to search for a specific character string
The following query finds products that contain the word Aerodynamic in the summary descriptions. The query returns the ProductID and the <Summary> element for such products.
--The product model description document uses
--namespaces. The WHERE clause uses the exit()
--method of the xml data type. Inside the exit method,
--the XQuery contains() function is used to
--determine whether the <Summary> text contains the word
--Aerodynamic.
USE AdventureWorks2022;
GO
WITH XMLNAMESPACES ('https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription' AS pd)
SELECT ProductModelID, CatalogDescription.query('
<Prod>
{ /pd:ProductDescription/@ProductModelID }
{ /pd:ProductDescription/pd:Summary }
</Prod>
') as Result
FROM Production.ProductModel
where CatalogDescription.exist('
/pd:ProductDescription/pd:Summary//text()
[contains(., "Aerodynamic")]') = 1
Results
ProductModelID Result
-------------- ---------
28 <Prod ProductModelID="28">
<pd:Summary xmlns:pd=
"https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription">
<p1:p xmlns:p1="http://www.w3.org/1999/xhtml">
A TRUE multi-sport bike that offers streamlined riding and
a revolutionary design. Aerodynamic design lets you ride with
the pros, and the gearing will conquer hilly roads.</p1:p>
</pd:Summary>
</Prod>