Note:You can specify at most one
XMLTable maps the result of an XQuery evaluation into relational rows and columns. You can query the result returned by the function as a virtual relational table using SQL.
XMLNAMESPACES clause contains a set of XML namespace declarations. These declarations are referenced by the XQuery expression (the evaluated
XQuery_string), which computes the row, and by the XPath expression in the
PATH clause of
XML_table_column, which computes the columns for the entire
XMLTable function. If you want to use qualified names in the
PATH expressions of the
COLUMNS clause, then you need to specify the
XQuery_string is a literal string. It is a complete XQuery expression and can include prolog declarations. The value of XQuery_string serves as input to the XMLTable function; it is this XQuery result that is decomposed and stored as relational data.
expr in the
XML_passing_clause is an expression returning an
XMLType or an instance of a SQL scalar data type that is used as the context for evaluating the XQuery expression. You can specify only one
expr in the
PASSING clause without an identifier. The result of evaluating each
expr is bound to the corresponding identifier in the
XQuery_string. If any
expr that is not followed by an
AS clause, then the result of evaluating that expression is used as the context item for evaluating the
XQuery_string. This clause supports only passing by value, not passing by reference. Therefore, the
VALUE keywords are optional and are provided for semantic clarity.
REF clause causes the result of the XQuery evaluation to be returned by reference. This allows you to refer to any part of the source data in the
If you omit this clause, then the result of the XQuery evaluation is returned by value. That is, a copy of the targeted nodes is returned instead of a reference to the actual nodes. In this case, you cannot refer to any data that is not in the returned copy in the
XML_table_column clause. In particular, you cannot refer to data that precedes the targeted nodes in the source data.
COLUMNS clause defines the columns of the virtual table to be created by
If you omit the
COLUMNS clause, then
XMLTable returns a row with a single
XMLType pseudocolumn named
ORDINALITY specifies that
column is to be a column of generated row numbers. There must be at most one
ORDINALITY clause. It is created as a
For each resulting column except the
ORDINALITY column, you must specify the column data type, which can be
XMLType or any other data type.
If the column data type is
XMLType, then specify the
XMLTYPE clause. If you specify the optional
REF clause, then a reference to the source data targeted by the
PATH expression is returned as the column content. Otherwise,
column contains a copy of that targeted data.
XMLType data by reference lets you specify other columns whose paths target nodes in the source data that are outside those targeted by the
PATH expression for column.
If the column data type is any other data type, then specify
PATH clause specifies that the portion of the XQuery result that is addressed by XQuery expression string is to be used as the column content.
If you omit
PATH, then the XQuery expression
column is assumed. For example:
XMLTable(... COLUMNS xyz)
is equivalent to
XMLTable(... COLUMNS xyz PATH 'XYZ')
You can use different
PATH clauses to split the XQuery result into different virtual-table columns.
DEFAULT clause specifies the value to use when the
PATH expression results in an empty sequence. Its
expr is an XQuery expression that is evaluated to produce the default value.
See Also:Oracle XML DB Developer's Guide for more information on the
XMLTablefunction, including additional examples, and on XQuery in general
The following example converts the result of applying the XQuery
'/Warehouse' to each value in the
warehouse_spec column of the
warehouses table into a virtual relational table with columns
SELECT warehouse_name warehouse, warehouse2."Water", warehouse2."Rail" FROM warehouses, XMLTABLE('/Warehouse' PASSING warehouses.warehouse_spec COLUMNS "Water" varchar2(6) PATH 'WaterAccess', "Rail" varchar2(6) PATH 'RailAccess') warehouse2; WAREHOUSE Water Rail ----------------------------------- ------ ------ Southlake, Texas Y N San Francisco Y N New Jersey N N Seattle, Washington N Y