Oracle XMLTABLE tips

The XMLTABLE function returns the content of an XML document or an element in a relational table format.

The prototype for defining a XMLTABLE function is shown below,

For understanding this function, the below demo table and data are created in the database.

table EMPLOYEE_DETAILS created.

1 rows inserted.

1 rows inserted.

1 rows inserted.

1 rows inserted.

1 rows inserted.

committed.

When the XMLTYPE column of the EMPLOYEE_DETAILS table is passed as an input to the XMLTABLE function with appropriate paths, suitable data types and joined with its underlying table, the SQL returns a relation view of the XML document as shown below,

XMLTABLE processes an XQuery program and returns rows.

SELECT
   XMLELEMENT(N,COLUMN_VALUE) N
FROM
   XMLTABLE
   (
      '1 to 10'
   );

N
----------
< N>1</N>
< N>2</N>
< N>3</N>
< N>4</N>
< N>5</N>
< N>6</N>
< N>7</N>
< N>8</N>
< N>9</N>
< N>10</N>

The very short XQuery program returns a sequence of numbers from 1 to 10. XMLTABLE returns a row for each value.

XQUERY programs can generate rows like XMLSEQUENCE.

SELECT
   NAME
FROM
   WORLD,
   XMLTABLE
   ('
      for $CANTON in $COUNTRY/COUNTRY/CANTON_LIST/CANTON
      where $CANTON//LANGUAGE="Italian"
      order by $CANTON/@ID
      return $CANTON
   '
   PASSING
      OBJECT_VALUE
   AS
      COUNTRY
   COLUMNS
      NAME XMLTYPE PATH '/CANTON/NAME'
   ); 

NAME
---------------------------
< NAME>Graubuenden</NAME>
< NAME>Ticino</NAME>

XMLTABLE processes the COUNTRY and returns a row for each canton where the language Italian exists. The rows are sorted by ID and the column NAME is returned for the name of the canton.

XMLEXISTS (11gR1) is a Boolean function similar to EXISTSNODEwith the XQuery syntax.

SELECT
   XMLFOREST(EMPNO, ENAME, JOB)
FROM
   EMP
WHERE
   XMLEXISTS
   (
      '/[JOB="ANALYST"]'
      PASSING
      XMLFOREST(EMPNO, ENAME, JOB)
   ); 

XMLFOREST(EMPNO,ENAME,JOB)
----------------------------------------
< EMPNO>7788</EMPNO>
< ENAME>SCOTT</ENAME>
< JOB>ANALYST</JOB> 

<EMPNO>7902</EMPNO>
< ENAME>FORD</ENAME>
< JOB>ANALYST</JOB>

The XPATH expression searches for analysts in the generated content.

Besides selecting literals and column values, XQuery has multiple functions. The function ora:viewis an Oracle-specific addition to the XQuery language that queries a relational table or view:

SELECT
   *
FROM
   XMLTABLE
   (
      '
         for $i in ora:view("EMP"), $j in ora:view("DEPT")
         where $i//JOB="ANALYST" and $i//DEPTNO=$j//DEPTNO
         return (<EMP>{$i//EMPNO}{$i//ENAME}{$j//DNAME}</EMP>)
      '
      COLUMNS
         EMP XMLTYPE PATH '/EMP'
   );

EMP
-------------------------------------------------------------------------
< EMP><EMPNO>7902</EMPNO><ENAME>FORD</ENAME><DNAME>RESEARCH</DNAME></EMP>
< EMP><EMPNO>7788</EMPNO><ENAME>SCOTT</ENAME><DNAME>RESEARCH</DNAME></EMP>

---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |     1 |    59 |     7  (15)| 00:00:01 |
|*  1 |  HASH JOIN         |      |     1 |    59 |     7  (15)| 00:00:01 |
|*  2 |   TABLE ACCESS FULL| EMP  |     1 |    39 |     3   (0)| 00:00:01 |
|   3 |   TABLE ACCESS FULL| DEPT |     4 |    80 |     3   (0)| 00:00:01 |
---------------------------------------------------------------------------

The XML Query selects directly from the EMP and DEPT tables. Note the execution plan: Oracle is doing a hash join of EMP and DEPT, which means the XML Query is analyzed before execution and the optimizer chooses the best possible execution plan. The columns clause defines the name and datatype of the columns that are returned. Without the columns clause, only one column named COLUMN_NAME containing an XMLTYPE is returned. The path string identifies the location of the column within the XML hierarchy.

XML Query can now be an expression.

CREATE TABLE
   T
AS
SELECT
   TABLE_NAME
FROM
   USER_TABLES;
SELECT
   TABLE_NAME,
   C
FROM
   T,
   XMLTABLE
   (
      (
         SELECT
            '
               let $j := ora:view("'||T.TABLE_NAME||'")
               return <c>{count($j)}</c>
            '
         FROM
            DUAL
      )
      COLUMNS C NUMBER PATH '/C'
   );

TABLE_NAME                              C
------------------------------ ----------
SALGRADE                                5
BONUS                                   0
EMP                                    14
DEPT                                    4

The query is built dynamically. The table name here is selected from table T, so it could be any expression.

Oracle Training from Don Burleson  The best on site "Oracle training classes" are just a phone call away! You can get personalized Oracle training by Donald Burleson, right at your shop!

Burleson is the American Team Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum. Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications. Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:   and include the URL for the page.                      Burleson Consulting The Oracle of Database Support Oracle Performance Tuning Remote DBA Services   Copyright © 1996 -  2020 All rights reserved by Burleson Oracle ® is the registered trademark of Oracle Corporation.