Functions on Boolean Values - not Function
Applies to: 
SQL Server
Returns TRUE if the effective Boolean value of $arg is false, and returns FALSE if the effective Boolean value of $arg is true.
Syntax
fn:not($arg as item()*) as xs:boolean
Arguments
$arg
A sequence of items for which there is an effective Boolean value.
Examples
This topic provides XQuery examples against XML instances that are stored in various xml type columns in the AdventureWorks database.
A. Using the not() XQuery function to find product models whose catalog descriptions do not include the <Specifications> element.
The following query constructs XML that contains product model IDs for product models whose catalog descriptions do not include the <Specifications> element.
WITH XMLNAMESPACES ('https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription' AS pd)
SELECT ProductModelID, CatalogDescription.query('
<Product
ProductModelID="{ sql:column("ProductModelID") }"
/>
') as Result
FROM Production.ProductModel
WHERE CatalogDescription.exist('
/pd:ProductDescription[not(pd:Specifications/*)] '
) = 0
Note the following from the previous query:
Because the document uses namespaces, the sample uses the WITH NAMESPACES statement. Another option is to use the declare namespace keyword in the XQuery Prolog to define the prefix.
The query then constructs the XML that includes the <
Product> element and its ProductModelID attribute.The WHERE clause uses the exist() method (XML data type) to filter the rows. The exist() method returns True if there are <ProductDescription> elements that do not have <Specification> child elements. Note the use of the not() function.
This result set is empty, because each product model catalog description includes the <Specifications> element.
B. Using the not() XQuery function to retrieve work center locations that do not have a MachineHours attribute
The following query is specified against the Instructions column. This column stores manufacturing instructions for the product models.
For a particular product model, the query retrieves work center locations that do not specify MachineHours. That is, the attribute MachineHours is not specified for the <Location> element.
SELECT ProductModelID, Instructions.query('
declare namespace AWMI="https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelManuInstructions" ;
for $i in /AWMI:root/AWMI:Location[not(@MachineHours)]
return
<Location LocationID="{ $i/@LocationID }"
LaborHrs="{ $i/@LaborHours }" >
</Location>
') as Result
FROM Production.ProductModel
WHERE ProductModelID=7
In the preceding query, note the following:
The declarenamespace in XQuery Prolog defines the Adventure Works manufacturing instructions namespace prefix. It represents the same namespace used in the manufacturing instructions document.
In the query, the not(@MachineHours) predicate returns True if there is no MachineHours attribute.
This is the result:
ProductModelID Result
-------------- --------------------------------------------
7 <Location LocationID="30" LaborHrs="1"/>
<Location LocationID="50" LaborHrs="3"/>
<Location LocationID="60" LaborHrs="4"/>
Implementation Limitations
These are the limitations:
- The not() function only supports arguments of type xs:boolean, or node()*, or the empty sequence.