XML functions

The following table describes the supported SQL XML functions.

Function	Description
DEPTH	Returns the number of levels in the path specified by the UNDER_PATH condition using the same correlation variable. Used only with UNDER_PATH and EQUALS_PATH conditions.
EXISTSNODE	Determines whether traversing an XMLType document with a specified XPath expression returns any nodes. Accepts an XMLType instance and a VARCHAR2 XPath string, with an optional namespace_string for namespace mapping. Returns 1 if nodes are found, otherwise 0.
EXTRACT (XML)	Applies a VARCHAR2 XPath expression to an XMLType document and returns an XMLType fragment. Supports absolute paths (starting with /) or relative paths (defaulting to the root node). An optional namespace_string specifies namespace mapping when the XML uses prefixes.
EXTRACTVALUE	Returns a scalar value from an XMLType document based on an XPath expression. The result must be a single text node, attribute, or element with a single text child. Supports absolute paths (with /) or relative paths (defaulting to the root node).
PATH	Returns the relative path to the resource specified in the parent condition. Used only with UNDER_PATH and EQUALS_PATH conditions.
SYS_DBURIGEN	Generates a DBURIType URL for a specified column, attribute, or optionally a ROWID. The URL can be used to retrieve an XML document from the database.
SYS_XMLAGG	Aggregates XML documents or fragments from expr into a single XML document. Adds an enclosing ROWSET element by default. A custom format can be specified with an XMLFormat object.
SYS_XMLGEN	Returns an XMLType containing an XML document generated from expr. The argument can be a scalar value, a user-defined type, or an XMLType.
XMLAGG	Aggregates a collection of XML fragments into a single XML document, excluding any arguments that return NULL.
XMLCAST	Casts value_expression to the scalar SQL data type specified by datatype. The argument datatype can be NUMBER, VARCHAR2, CHAR, CLOB, BLOB, REF XMLTYPE, or any datetime type.
XMLCDATA	Generates a CDATA section from value_expr, which must resolve to a string.
XMLCOLATTVAL	Creates an XML fragment from a column and expands it so that each fragment uses the column name as the attribute name.
XMLCOMMENT	Generates an XML comment from value_expr, which must resolve to a string. The string cannot contain two consecutive hyphens (--).
XMLCONCAT	Concatenates a series of XMLType instances for each row and returns the combined result. Serves as the inverse of XMLSequence.
XMLDIFF	Compares two XML documents and returns an XMLType diff document that conforms to the Xdiff schema. Acts as the SQL interface to the XmlDiff C API.
XMLELEMENT	Creates an XML element with a specified name, optional attributes, and content arguments, and returns it as an XMLType. Similar to SYS_XMLGen, but supports attributes and does not allow formatting with XMLFormat.
XMLEXISTS	Checks whether an XQuery expression returns a nonempty sequence. Returns TRUE if the result is nonempty; otherwise, returns FALSE. The XQuery_string can include variables bound with the XML_passing_clause.
XMLFOREST	Converts each argument to XML and returns an XML fragment that concatenates the converted arguments.
XMLISVALID	Checks whether an XMLType instance conforms to its XML schema. Does not modify the validation status recorded for the XMLType instance.
XMLPARSE	Parses the evaluated result of value_expr and generates an XMLType instance. If value_expr resolves to NULL, the function returns NULL.
XMLPATCH	Applies changes to an XML document as specified by a patch expression and returns the patched document as an XMLType. Serves as the SQL interface to the XmlPatch C API.
XMLPI	Generates an XML processing instruction using identifier and optionally the evaluated result of value_expr. Processing instructions provide applications with information on how to handle all or part of an XML document.
XMLQUERY	Queries XML data in SQL by evaluating an XQuery expression. Accepts a string literal for the expression, an optional context item, and bind variables, and returns the result of the evaluation.
XMLROOT	Creates a new XML value by adding version and standalone properties to the root (prolog) of an existing XML value. Returns an error if the input already contains a prolog, or NULL if the input is NULL.
XMLSEQUENCE	Takes either an XMLType input and returns a varray of its top-level nodes, or a REFCURSOR input (optionally with an XMLFormat) and returns an XMLSequence of XML documents for each row in the cursor. The first form is superseded by XMLTable for more readable SQL.
XMLSERIALIZE	Creates a string or LOB containing the serialized contents of value_expr.
XMLTABLE	Maps the result of an XQuery evaluation into relational rows and columns and returns it as a virtual table that can be queried with SQL.
XMLTRANSFORM	Applies an XSL style sheet (XMLType) to an XMLType instance and returns the transformed result as an XMLType.