-- ============================================================
-- sample code on using the SQL Server xml method exist()
-- several samples shown
-- Donabel Santos
-- ============================================================

DECLARE @xmlSnippet XML
DECLARE @id SMALLINT
DECLARE @value VARCHAR(20)

SET @xmlSnippet =
'
<ninjaElement id="1">SQL Server Ninja</ninjaElement>
<ninjaElement id="2">SharePoint Ninja</ninjaElement>
<ninjaElement id="3">ASP.NET Ninja</ninjaElement>
'

-- this is what we will look for
SET @id    = 2
SET @value ='SQL Server Ninja'

-- note exist() will return only either :
-- 1 (true) or 0 (false)

-- check if a node called ninjaElement exists
-- at any level in the XML snippet
SELECT @xml.exist('//ninjaElement')

-- check if a node called bar exists
SELECT @xml.exist('//bar')

-- check if attribute id exists anywhere
SELECT @xml.exist('//@id')

-- check if attribute id exists within a ninjaElement tag
SELECT @xml.exist('//ninjaElement[@id]')

-- check if the id attribute equals to what we saved
-- in the @id variable
SELECT @xml.exist('/ninjaElement[@id=sql:variable("@id")]')

-- check if the node text equals to what
-- we saved in the @value variable
SELECT @xml.exist('/ninjaElement[text()=sql:variable("@value")]')

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