How to display the NULL records by multiple XMLTABLE()

Question

First, let me provide the testing data of INSERT and CREATE TABLE sql:
create table xml_t2 (xml_raw XMLTYPE);insert sql, a bit long.....just copy and paste then run it will be OK!
the system warns: Your message exceeds the maximum length of 30000 characters.
So, I place it on the mediafire shariing space
http://www.mediafire.com/?npmot6lgl86dgliTesting SQL:
SELECT t1.years, t1.months,t1.days,t1.hours,t1.value,t2.value
        FROM xml_t2,
        XMLTABLE ('$d/cdata/F1' passing xml_raw as "d" COLUMNS years integer path '//year', months varchar(3) path '//month', days varchar(2) path '//day', hours varchar(2) path '//hour', mins varchar(2) path '//minute', value float path '//value') t1 ,
        XMLTABLE ('$d/cdata/F2' passing xml_raw as "d" COLUMNS years integer path '//year', months varchar(3) path '//month', days varchar(2) path '//day', hours varchar(2) path '//hour', mins varchar(2) path '//minute', value float path '//value') t2The condition for now is....In the xml data, I have deleted the month 'Jan' with <F2>tag which is in 2010.
That mean the output of XMLTABLE t2 will not contain the 'Jan' records but it is still remain in XMLTABLE t1.
The problem is that when I use the above SQL to show the t1.value, it will not display the t1.value in 2010 Jan.....it just skipped 'Jan' and becomes 'Feb'...
what i would prefer to display is something like this:
YEARS MONTHS DAYS HOURS t1_value t2_value
2009     Jan    01   01       8       8
2009     Jan    01   02       8     580
2009     Jan    02   01     580     580
2009     Jan    02   02     580     580
2009     Feb    01   01     440     440
2010     Jan    01   01     627     NULL
2010     Jan    01   02     627     NULL
2010     Jan    02   01     367     NULL
2010     Jan    02   02     367     NULL
2010     Feb    01   01     367     849
2010     Feb    01   02     849     849
..............So...the main problem is how to display back the record in JAN in 2010 in t1 XMLTABLE and assign null to the t2 XMLTABLE since it doen't contains this months record.
THANKS for help!!

Answer 1

Hi,
What's your database version?
Are you using binary XML storage? (This is the default in 11.2.0.2)
If not you have to explicitely specify it :
create table xml_t2 (xml_raw XMLTYPE)
xmltype column xml_raw store as securefile binary xml;Along with object-relational, it's the best storage strategy to use in conjunction with XMLIndex.
You should also use a structured XML index instead, it's more appropriate than the unstructured index you're currently using :
create index xml_t2_sxi on xml_t2 (xml_raw)
indextype is xdb.xmlindex
parameters (q'#
XMLTABLE xml_t2_xt '/cdata'
COLUMNS
YEARS  INTEGER    PATH 'F1/name/year',
MONTHS VARCHAR(3) PATH 'F1/name/month',
DAYS   VARCHAR(2) PATH 'F1/name/day',
HOURS  VARCHAR(2) PATH 'F1/name/hour',
MINS   VARCHAR(2) PATH 'F1/name/minute',
VALUE  FLOAT      PATH 'F1/name/value',
VALUE2 FLOAT      PATH 'F2/name/value'
call dbms_stats.gather_table_stats(user, 'XML_T2');Use the query provided by Stew and check the explain plan, you'll see the difference.