XMLTABLE

The XMLTABLE function uses XQuery to produce tabular output. The XMLTABLE function is implicitly a nested table and may be correlated to preceding FROM clause entries. XMLTABLE is part of the SQL/XML 2006 specification.

Usage:

XMLTABLE([<NSP>,] xquery-expression [<PASSING>] [COLUMNS <COLUMN>, ... )] AS name
COLUMN := name (FOR ORDINALITY | (datatype [DEFAULT expression] [PATH string]))

See XMLELEMENT for the definition of NSP - XMLNAMESPACES.

See XMLQUERY for the definition of PASSING.

See also XMLQUERY

Note
 See also XQuery Optimization

Parameters

  • The optional XMLNAMESPACES clause specifies the namepaces for use in the XQuery and COLUMN path expressions.

  • The xquery-expression should be a valid XQuery. Each sequence item returned by the xquery will be used to create a row of values as defined by the COLUMNS clause.

  • If COLUMNS is not specified, then that is the same as having the COLUMNS clause: "COLUMNS OBJECT_VALUE XML PATH '."', which returns the entire item as an XML value.

  • A FOR ORDINALITY column is typed as integer and will return the 1-based item number as its value.

  • Each non-ordinality column specifies a type and optionally a PATH and a DEFAULT expression.

  • If PATH is not specified, then the path will be the same as the column name.

Syntax Rules:

  • Only 1 FOR ORDINALITY column may be specified.

  • The columns names must not contain duplicates.

  • The blob datatype is supported, but there is only built-in support for xs:hexBinary values.  For xs:base64Binary, use a workaround of a PATH that uses the explicit value constructor "xs:base64Binary(<path>)".

  • The column expression must evaluate to a single value if a non-array type is expected.

  • If an array type is specified then an array will be returned unless there are no elements in the sequence, in which case a null value is returned.

  • An empty element is not a valid null value as it is effectively the empty string. The xsi:nil attribute should be used to define convey a null valued element.

Examples

Use of passing, returns 1 row [1]:

select * from xmltable('/a' PASSING xmlparse(document '<a id="1"/>') COLUMNS id integer PATH '@id') x

As a nested table:

select x.* from t, xmltable('/x/y' PASSING t.doc COLUMNS first string, second FOR ORDINALITY) x

Invalid multi-value:

select * from xmltable('/a' PASSING xmlparse(document '<a><b id="1"/><b id="2"/></a>') COLUMNS id integer PATH 'b/@id') x

Array multi-value:

select * from xmltable('/a' PASSING xmlparse(document '<a><b id="1"/><b id="2"/></a>') COLUMNS id integer[] PATH 'b/@id') x

Nil element. Without the nil attribute an exception would be thrown converting b to an integer value.

select * from xmltable('/a' PASSING xmlparse(document '<a xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><b xsi:nil="true"/></a>') COLUMNS id integer PATH 'b') x

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