Oracle XPath: Parent Node Attribute? - sql

Question

I'm an XPath newbie; I've found a way to do what I want, but wonder if there's another way that can save me some repetition in my code.
I have this table:
CREATE TABLE t (
quark_p1 VARCHAR2(4)
, quark_p2 VARCHAR2(7)
, quark_p3 VARCHAR2(6)
, one VARCHAR2(1)
, two VARCHAR2(1)
, three VARCHAR2(1)
, four VARCHAR2(1)
, five VARCHAR2(1)
, six VARCHAR2(1)
, seven VARCHAR2(1)
, eight VARCHAR2(1)
, nine VARCHAR2(1)
)
;
The following PL/SQL anonymous block does what I want, extracting into this table the structure from my given XML:
BEGIN
INSERT INTO t (
quark_p1
, quark_p2
, quark_p3
, one
, two
, three
, four
, five
, six
, seven
, eight
, nine
)
SELECT x.quark_p1
, x.quark_p2
, x.quark_p3
, x.one
, x.two
, x.three
, x.four
, x.five
, x.six
, x.seven
, x.eight
, x.nine
FROM XMLTABLE('/BASIS/QUARK'
PASSING XMLTYPE (
'<BASIS>
<QUARK P1="up" P2="charm" P3="bottom">
<NEST>
<ONE>A</ONE>
<TWO>B</TWO>
<THREE>C</THREE>
<FOUR>D</FOUR>
<FIVE>E</FIVE>
<SIX>F</SIX>
<SEVEN>G</SEVEN>
<EIGHT>H</EIGHT>
<NINE>I</NINE>
</NEST>
</QUARK>
<QUARK P1="up" P2="strange" P3="top">
<NEST>
<ONE>J</ONE>
<TWO>K</TWO>
<THREE>L</THREE>
<FOUR>M</FOUR>
<FIVE>N</FIVE>
<SIX>O</SIX>
<SEVEN>P</SEVEN>
<EIGHT>Q</EIGHT>
<NINE>R</NINE>
</NEST>
</QUARK>
</BASIS>')
COLUMNS quark_p1 VARCHAR2(4) PATH '#P1'
, quark_p2 VARCHAR2(7) PATH '#P2'
, quark_p3 VARCHAR2(6) PATH '#P3'
, one VARCHAR2(1) PATH 'NEST/ONE'
, two VARCHAR2(1) PATH 'NEST/TWO'
, three VARCHAR2(1) PATH 'NEST/THREE'
, four VARCHAR2(1) PATH 'NEST/FOUR'
, five VARCHAR2(1) PATH 'NEST/FIVE'
, six VARCHAR2(1) PATH 'NEST/SIX'
, seven VARCHAR2(1) PATH 'NEST/SEVEN'
, eight VARCHAR2(1) PATH 'NEST/EIGHT'
, nine VARCHAR2(1) PATH 'NEST/NINE'
) x;
END;
/
This results in the following, which is what I'm after:
SQL> SELECT * FROM t
2 ;
QUARK_P1 QUARK_P2 QUARK_P3 O T T F F S S E N
-------- -------- -------- - - - - - - - - -
up charm bottom A B C D E F G H I
up strange top J K L M N O P Q R
SQL>
Since the "NEST" level is repeated so often, I'd like to pull it up into the starting node, and still get the same results. I'm looking to do something like the following:
BEGIN
INSERT INTO t (
quark_p1
, quark_p2
, quark_p3
, one
, two
, three
, four
, five
, six
, seven
, eight
, nine
)
SELECT x.quark_p1
, x.quark_p2
, x.quark_p3
, x.one
, x.two
, x.three
, x.four
, x.five
, x.six
, x.seven
, x.eight
, x.nine
-- Notice, I changed the starting node from /BASIS/QUARK to /BASIS/QUARK/NEST....
FROM XMLTABLE('/BASIS/QUARK/NEST'
PASSING XMLTYPE (
'<BASIS>
<QUARK P1="up" P2="charm" P3="bottom">
<NEST>
<ONE>A</ONE>
<TWO>B</TWO>
<THREE>C</THREE>
<FOUR>D</FOUR>
<FIVE>E</FIVE>
<SIX>F</SIX>
<SEVEN>G</SEVEN>
<EIGHT>H</EIGHT>
<NINE>I</NINE>
</NEST>
</QUARK>
<QUARK P1="up" P2="strange" P3="top">
<NEST>
<ONE>J</ONE>
<TWO>K</TWO>
<THREE>L</THREE>
<FOUR>M</FOUR>
<FIVE>N</FIVE>
<SIX>O</SIX>
<SEVEN>P</SEVEN>
<EIGHT>Q</EIGHT>
<NINE>R</NINE>
</NEST>
</QUARK>
</BASIS>')
-- ...and I changed all the paths here
COLUMNS quark_p1 VARCHAR2(4) PATH '../#P1'
, quark_p2 VARCHAR2(7) PATH '../#P2'
, quark_p3 VARCHAR2(6) PATH '../#P3'
, one VARCHAR2(1) PATH 'ONE'
, two VARCHAR2(1) PATH 'TWO'
, three VARCHAR2(1) PATH 'THREE'
, four VARCHAR2(1) PATH 'FOUR'
, five VARCHAR2(1) PATH 'FIVE'
, six VARCHAR2(1) PATH 'SIX'
, seven VARCHAR2(1) PATH 'SEVEN'
, eight VARCHAR2(1) PATH 'EIGHT'
, nine VARCHAR2(1) PATH 'NINE'
) x;
END;
/
This seems to me like it should work, but I get this error:
FROM XMLTABLE('/BASIS/QUARK/NEST'
*
ERROR at line 28:
ORA-06550: line 28, column 10:
PL/SQL: ORA-19110: unsupported XQuery expression
ORA-06550: line 2, column 5:
PL/SQL: SQL Statement ignored
SQL>
Am I missing something simple, or can I not get there from here?
Thanks.

Answer 1

I was surprised to find from
How to get the name of the parent element in an Oracle XPath expression?
that it works if you just put "./" in front of the "../"