The XMLVALIDATE function returns a copy of the input XML
value augmented with information obtained from XML schema validation,
including default values and type annotations.

.-DOCUMENT-.
>>-XMLVALIDATE--(--+----------+--XML-expression----------------->
>--+--------------------------------------+--)-----------------><
'-| XML-validate-according-to-clause |-'
XML-validate-according-to-clause
|--ACCORDING TO XMLSCHEMA--+-ID--XML-schema-name-----------------------+-->
'-+-URI--XML-uri1-+--+--------------------+-'
'-NO NAMESPACE--' '-LOCATION--XML-uri2-'
>--+------------------------------+-----------------------------|
'-| XML-valid-element-clause |-'
XML-valid-element-clause
|--+---------------------+--ELEMENT--XML-element-name-----------|
+-NAMESPACE--XML-uri3-+
'-NO NAMESPACE--------'
- DOCUMENT
- Specifies that the XML value resulting from XML-expression must
be a well-formed XML document that conforms to XML Version 1.0.
- XML-expression
- An expression that returns a value of data type XML. If XML-expression is
an XML host variable or an implicitly or explicitly typed parameter
marker, the function performs a validating parse that strips ignorable
whitespace and the CURRENT IMPLICIT XMLPARSE OPTION setting is not
considered.
- XML-validate-according-to-clause
- Specifies the information that is to be used when validating the
input XML value.
- ACCORDING TO XMLSCHEMA
- Indicates that the XML schema information for validation is explicitly
specified. If this clause is not included, the XML schema information
must be provided in the content of the XML-expression value.
- ID XML-schema-name
- Specifies an SQL identifier for the XML schema that is to be used
for validation. The name, including the implicit or explicit SQL schema
qualifier, must uniquely identify an existing XML schema in the XML
schema repository at the current server. If no XML schema by this
name exists in the implicitly or explicitly specified SQL schema,
an error is returned.
- URI XML-uri1
- Specifies the target namespace URI of the XML schema that is to
be used for validation. The value of XML-uri1 specifies a URI
as a character string constant that is not empty. The URI must be
the target namespace of a registered XML schema and, if no LOCATION
clause is specified, it must uniquely identify the registered XML
schema.
- NO NAMESPACE
- Specifies that the XML schema for validation has no target namespace.
The target namespace URI is equivalent to an empty character string
that cannot be specified as an explicit target namespace URI.
- LOCATION XML-uri2
- Specifies the XML schema location URI of the XML schema that is
to be used for validation. The value of XML-uri2 specifies
a URI as a character string constant that is not empty. The XML schema
location URI, combined with the target namespace URI, must identify
a registered XML schema, and there must be only one such XML schema
registered.
- XML-valid-element-clause
- Specifies that the XML value in XML-expression must have
the specified element name as the root element of the XML document.
- NAMESPACE XML-uri3 or NO NAMESPACE
- Specifies the target namespace for the element that is to be validated.
If neither clause is specified, the specified element is assumed to
be in the same namespace as the target namespace of the registered
XML schema that is to be used for validation.
- NAMESPACE XML-uri3
- Specifies the namespace URI for the element that is to be validated.
The value of XML-uri3 specifies a URI as a character string
constant that is not empty. This can be used when the registered XML
schema that is to be used for validation has more than one namespace.
- NO NAMESPACE
- Specifies that the element for validation has no target namespace.
The target namespace URI is equivalent to an empty character string
which cannot be specified as an explicit target namespace URI.
- ELEMENT xml-element-name
- Specifies the name of a global element in the XML schema that
is to be used for validation. The specified element, with implicit
or explicit namespace, must match the root element of the value of XML-expression.
The result of the function is XML. If the value of XML-expression can
be null, the result can be null; if the value of XML-expression is
null, the result is the null value. The CCSID of the result is determined
from the XML-expression.
The XML validation process is
performed on a serialized XML value. Because XMLVALIDATE is invoked
with an argument of type XML, this value is automatically serialized
prior to validation processing with the following two exceptions:
- If the argument to XMLVALIDATE is an XML host variable or an implicitly
or explicitly typed parameter marker, then a validating parse operation
is performed on the input value (no implicit non-validating parse
is performed and the CURRENT IMPLICIT XMLPARSE OPTION setting is not
considered).
- If the argument to XMLVALIDATE is an XMLPARSE invocation using
the option PRESERVE WHITESPACE, then the XML parsing and XML validation
of the document may be combined into a single validating parse operation.
To validate a document whose root element does not have a
namespace, an xsi:noNamespaceSchemaLocation attribute
must be present on the root element.
Notes
Determining
the XML schema: The XML schema can be specified explicitly as
part of the XMLVALIDATE invocation or determined from the XML schema
information in the input XML value. If the XML schema information
is not specified during invocation, the target namespace and the schema
location in the input XML value are used to identify the registered
schema for validation. If an explicit XML schema is not specified,
the input XML value must contain an XML schema information hint. Explicit
or implicit XML schema information must identify a registered XML
schema, and there must be only one such registered XML schema.
If
you do not specify an XML schema document, the database server looks
in the input document for an xsi:schemaLocation or xsi:noNamespaceSchemaLocation attribute
that identifies the XML schema document. xsi:schemaLocation or xsi:noNamespaceSchemaLocation attributes
are defined by the XML schema specification and are called XML schema
hints. An xsi:schemaLocation attribute contains one or more
pairs of values that help to locate the XML schema document. The first
value in each pair is a namespace and the second value is a hint that
indicates where to find the XML schema for the namespace. An xsi:noNamespaceSchemaLocation value
contains only a hint. If an XML schema document is specified in the
XMLVALIDATE function, it overrides the xsi:schemaLocation or xsi:noNamespaceSchemaLocation attribute.
Specifying
the XML schema explicitly on the XMLVALIDATE function avoids the parsing
required to locate the XML schema information hint in the XML value.
XML
schema authorization: The XML schema used for validation must
be registered in the XML schema repository prior to use. The privileges
held by the authorization ID of the statement must include at least
one of the following:
- USAGE privilege on the XML schema that is to be used during validation
- Administrative authority
Examples
- Validate using the XML schema identified by the XML schema hint
in the XML instance document.
INSERT INTO T1(XMLCOL)
VALUES (XMLVALIDATE(?))
Assume
that the input parameter marker is bound to an XML value that contains
the XML schema information.
<po:order
xmlns:po='http://my.world.com'
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://my.world.com/world.xsd" >
...
</po:order>
Further, assume that the XML schema
that is associated with the target namespace "http://my.world.com"
and by schemaLocation hint "http://my.world.com/world.xsd" is found
in the XML schema repository
Based on these assumptions, the
input XML value will be validated according to that XML schema.
- Validate using the XML schema identified by the SQL name PODOCS.WORLDPO
INSERT INTO T1(XMLCOL)
VALUES(
XMLVALIDATE(? ACCORDING TO XMLSCHEMA ID PODOCS.WORLDPO))
Assuming that the XML schema that is associated with
SQL name PODOC.WORLDPO is found in the XML schema repository, the
input XML value will be validated and the type annotated according
to that XML schema.
- Validate a specified element of the XML value.
INSERT INTO T1(XMLCOL)
VALUES(
XMLVALIDATE(?
ACCORDING TO XMLSCHEMA ID FOO.WORLDPO
NAMESPACE 'http://my.world.com/Mary'
ELEMENT "po"))
Assuming that the XML schema that is associated with
SQL name FOO.WORLDPO is found in the XML schema repository, the XML
schema will be validated against the element "po", whose namespace
is "http://my.world.com/Mary".
- XML schema is identified by target namespace and schema location.
INSERT INTO T1(XMLCOL)
VALUES(
XMLVALIDATE(?
ACCORDING TO XMLSCHEMA URI 'http://my.world.com'
LOCATION 'http://my.world.com/world.xsd'))
Assuming that an XML schema associated with the target
namespace "http://my.world.com" and by schemaLocation hint "http://my.world.com/world.xsd"
is found in the XML schema repository, the input XML value will be
validated according to that XML schema.