XML: isnil invalid element

Question

I have the following XSD snippet:
<xs:element name="SSN" nillable="true" minOccurs="0"><xs:annotation><xs:documentation>SSN</xs:documentation></xs:annotation><xs:simpleType><xs:restriction base="xs:string"><xs:pattern value="\d{9}"/></xs:restriction></xs:simpleType>
And the corresponding XML:
<Patient>
<ProviderPatientNo>00202000</ProviderPatientNo>
<LastName>B </LastName>
<FirstName>Savannah</FirstName>
<SSN>409850124</SSN>
<DOB>1998-06-17</DOB>
<Gender>1</Gender>
<Race>8</Race>
<Ethnicity>3</Ethnicity>
<PhoneAssessment>
<ProviderPhoneAssessmentId>00F62E2A-B726-4573-B459-E216AC78BA06</ProviderPhoneAssessmentId>
<CallEndDate>2013-09-16</CallEndDate>
<CallEndTime>11:30:00</CallEndTime>
<CallDisposition>5</CallDisposition>
</PhoneAssessment>
</Patient>
<Patient>
<ProviderPatientNo>00202001</ProviderPatientNo>
<LastName>C</LastName>
<FirstName>Kylie</FirstName>
<SSN isnil="true" />
<DOB>2003-06-24</DOB>
<Gender>1</Gender>
<Race>1</Race>
<Ethnicity>2</Ethnicity>
<PhoneAssessment>
<ProviderPhoneAssessmentId>01089482-E878-4288-B103-A0F28B0A33EC</ProviderPhoneAssessmentId>
<CallEndDate>2013-09-25</CallEndDate>
<CallEndTime>18:12:00</CallEndTime>
<CallDisposition>1</CallDisposition>
</PhoneAssessment>
</Patient>
I'm trying to validate the SSN in this XML. But I get the following error:
The 'isnil' attribute is not declared.
The 'http://www.tn.gov/mental/Schemas/CrisisAssessment:SSN' element is invalid - The value '' is invalid according to its datatype 'String' - The Pattern constraint failed.
How do I fix this? I have tried various variations of this.
Ryan D

Answer 1

I got this to work.  Russ is right, the usual way to pass round nulls in XML is with xsi:nil, eg
USE tempdb
GO
SET NOCOUNT ON
GO
IF OBJECT_ID('dbo.ssn_test') IS NOT NULL DROP TABLE dbo.ssn_test
GO
IF EXISTS (SELECT * FROM sys.xml_schema_collections WHERE name = N'xsc_test' )
DROP XML SCHEMA COLLECTION xsc_test
GO
CREATE XML SCHEMA COLLECTION xsc_test
AS '<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
<!-- SSN Type -->
<xs:simpleType name="SSN_type">
<xs:restriction base="xs:token">
<xs:pattern value="[0-9]{9}|"/>
</xs:restriction>
</xs:simpleType>
<xs:element name="Patients">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="Patient">
<xs:complexType>
<xs:sequence>
<xs:element name="ProviderPatientNo" type="xs:unsignedInt" />
<xs:element name="LastName" type="xs:string" />
<xs:element name="FirstName" type="xs:string" />
<xs:element name="SSN" nillable="true">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="SSN_type" >
<xs:attribute name="nil" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:element name="DOB" type="xs:date" />
<xs:element name="Gender" type="xs:unsignedByte" />
<xs:element name="Race" type="xs:unsignedByte" />
<xs:element name="Ethnicity" type="xs:unsignedByte" />
<xs:element name="PhoneAssessment">
<xs:complexType>
<xs:sequence>
<xs:element name="ProviderPhoneAssessmentId" type="xs:string" />
<xs:element name="CallEndDate" type="xs:date" />
<xs:element name="CallEndTime" type="xs:time" />
<xs:element name="CallDisposition" type="xs:unsignedByte" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>'
GO
CREATE TABLE dbo.ssn_test ( rowId INT IDENTITY PRIMARY KEY, yourXML XML(xsc_test) )
GO
INSERT INTO dbo.ssn_test
SELECT '<Patients xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<Patient>
<ProviderPatientNo>00202000</ProviderPatientNo>
<LastName>B </LastName>
<FirstName>Savannah</FirstName>
<SSN>409850124</SSN>
<DOB>1998-06-17</DOB>
<Gender>1</Gender>
<Race>8</Race>
<Ethnicity>3</Ethnicity>
<PhoneAssessment>
<ProviderPhoneAssessmentId>00F62E2A-B726-4573-B459-E216AC78BA06</ProviderPhoneAssessmentId>
<CallEndDate>2013-09-16</CallEndDate>
<CallEndTime>11:30:00</CallEndTime>
<CallDisposition>5</CallDisposition>
</PhoneAssessment>
</Patient>
<Patient>
<ProviderPatientNo>00202001</ProviderPatientNo>
<LastName>C</LastName>
<FirstName>Kylie</FirstName>
<SSN xsi:nil="true" />
<DOB>2003-06-24</DOB>
<Gender>1</Gender>
<Race>1</Race>
<Ethnicity>2</Ethnicity>
<PhoneAssessment>
<ProviderPhoneAssessmentId>01089482-E878-4288-B103-A0F28B0A33EC</ProviderPhoneAssessmentId>
<CallEndDate>2013-09-25</CallEndDate>
<CallEndTime>18:12:00</CallEndTime>
<CallDisposition>1</CallDisposition>
</PhoneAssessment>
</Patient>
</Patients>'
GO
SELECT *
FROM dbo.ssn_test