问题
I've written simple Oracle queries to extract XMLTYPE data before, but this XML is different - I need to pull information from attributes, child elements, and their respective attributes. I also would like to write an INSERT statement as well (preferably one that is able to find the highest option value and add 1). Consider the following XML:
<metadata>
<fields>
<field name="cusInt01" label="Reference point">
<option value="1">CB</option>
<option value="2">CF</option>
<option value="3">DF</option>
<option value="4">EKB</option>
<option value="5">ES</option>
<option value="6">GL</option>
<option value="7">GR</option>
<option value="8">KB</option>
<option value="9">KBE</option>
<option value="10">MSL</option>
<option value="11">PT</option>
<option value="12">RB</option>
<option value="13">RF</option>
<option value="14">RT</option>
<option value="15">UN</option>
<option value="16">UNK</option>
</field>
</fields>
</metadata>
I can write, for instance, a query to extract all of the field names:
select
field_names.*
FROM
metadata m,
XMLTABLE('/metadata/fields/field'
PASSING xmltype(m.xml_string)
COLUMNS field_name VARCHAR(32) PATH '@name') field_names;
How do I write a query that can extract all the different information in a tabular form? How do I, for instance, display it as:
field_name | field_label | option_value | option_label
cusInt01 Reference point 1 CB
cusInt01 Reference point 2 CF
cusInt01 Reference point 2 DF
... etc. Thoughts? I've been trying to cobble a query together but so far spinning my wheels.
回答1:
In your example, the data is at multiple levels. Each field can have many option.
So, you must break up field as well as option elements with XMLTable.
First, you should break field elements, where option elements are mapped as XMLType. Then pass it to second XMLTable to further break it down.
Data Setup:
CREATE TABLE metadata (xml_string VARCHAR2 (2000));
INSERT INTO metadata
VALUES ('<metadata>
<fields>
<field name="cusInt01" label="Reference point">
<option value="1">CB</option>
<option value="2">CF</option>
<option value="3">DF</option>
<option value="4">EKB</option>
<option value="5">ES</option>
<option value="6">GL</option>
<option value="7">GR</option>
<option value="8">KB</option>
<option value="9">KBE</option>
<option value="10">MSL</option>
<option value="11">PT</option>
<option value="12">RB</option>
<option value="13">RF</option>
<option value="14">RT</option>
<option value="15">UN</option>
<option value="16">UNK</option>
</field>
</fields>
</metadata>');
COMMIT;
Query:
SELECT field.field_name,
field.field_label,
options.option_value,
options.option_label
FROM metadata m,
XMLTABLE (
'metadata/fields/field'
PASSING xmltype (m.xml_string)
COLUMNS field_name VARCHAR2 (32) PATH '@name',
field_label VARCHAR2 (32) PATH '@label',
field_options XMLTYPE PATH 'option') field,
XMLTABLE (
'option'
PASSING field.field_options
COLUMNS option_value NUMBER PATH '@value',
option_label VARCHAR2 (10) PATH '/') options;
Result:
FIELD_NAME FIELD_LABEL OPTION_VALUE OPTION_LABEL
-------------------------------------------------------------
cusInt01 Reference point 1 CB
cusInt01 Reference point 2 CF
cusInt01 Reference point 3 DF
cusInt01 Reference point 4 EKB
cusInt01 Reference point 5 ES
cusInt01 Reference point 6 GL
cusInt01 Reference point 7 GR
cusInt01 Reference point 8 KB
cusInt01 Reference point 9 KBE
cusInt01 Reference point 10 MSL
cusInt01 Reference point 11 PT
cusInt01 Reference point 12 RB
cusInt01 Reference point 13 RF
cusInt01 Reference point 14 RT
cusInt01 Reference point 15 UN
cusInt01 Reference point 16 UNK
Similar example at Oracle XML DB Developer's Guide.
回答2:
In addition to Eat A Peach's answer, I developed some INSTEAD OF queries to insert and update data. They're still in development so a tad rough but I figured I'd post them here in case someone might find them handy.
CREATE OR REPLACE VIEW FIELD_OPTIONS AS
select
s.id as space_id,
s.prefix_code,
fields.name AS FIELD_NAME,
fields.label AS FIELD_LABEL,
options.value as OPTION_VALUE,
options.label AS OPTIONS_LABEL,
options.mapping AS OPTIONS_MAPPING
FROM
metadata m,
spaces s,
XMLTABLE('/metadata/fields/field'
PASSING xmltype(m.xml_string)
COLUMNS name VARCHAR(32) PATH '@name',
label VARCHAR(64) PATH '@label',
options XMLTYPE PATH 'option') fields,
XMLTABLE('/option'
PASSING fields.options
COLUMNS value NUMBER PATH '@value',
label VARCHAR(64) PATH '.',
mapping VARCHAR(64) PATH '@mapping') options
where
s.metadata_id = m.id;
CREATE OR REPLACE TRIGGER INSERT_FIELD_OPTIONS
INSTEAD OF INSERT ON FIELD_OPTIONS
FOR EACH ROW
DECLARE
field_name VARCHAR(32);
space_prefix_code VARCHAR(32);
new_option_num NUMBER;
new_option_label VARCHAR(64);
new_option_mapping VARCHAR(64);
BEGIN
space_prefix_code:=:NEW.prefix_code;
field_name:=:NEW.field_name;
new_option_label:=:NEW.options_label;
new_option_mapping:=:NEW.options_mapping;
select --TODO: find out if options.value = 0
max(options.value)+1 INTO new_option_num
FROM
metadata m,
spaces s,
XMLTABLE('/metadata/fields/field'
PASSING xmltype(m.xml_string)
COLUMNS name VARCHAR(32) PATH '@name',
label VARCHAR(64) PATH '@label',
options XMLTYPE PATH 'option') fields,
XMLTABLE('/option'
PASSING fields.options
COLUMNS value NUMBER PATH '@value',
label VARCHAR(64) PATH '.') options
where
s.metadata_id = m.id AND
s.prefix_code = space_prefix_code AND
fields.name=field_name;
update metadata set
xml_string=(INSERTCHILDXML(XMLTYPE(xml_string),
'/metadata/fields/field[@name=''' || field_name || ''']',
'option',
XMLTYPE('<option mapping="' || new_option_mapping || '" value="' || TO_CHAR(new_option_num) || '">' || new_option_label || '</option>'))).getclobval() --must convert to clob as it is stored in the database that way
WHERE
id =(select metadata_id from spaces where prefix_code = space_prefix_code);
DBMS_OUTPUT.put_line(CHR(9) || TO_CHAR(SQL%ROWCOUNT)||' rows updated');
END;
/
CREATE OR REPLACE TRIGGER UPDATE_FIELD_OPTIONS
INSTEAD OF UPDATE ON FIELD_OPTIONS
FOR EACH ROW
DECLARE
field_name VARCHAR(32);
space_prefix_code VARCHAR(32);
new_options_label VARCHAR(64);
new_option_mapping VARCHAR(64);
new_option_value VARCHAR(64);
BEGIN
space_prefix_code:=:NEW.prefix_code;
field_name:=:NEW.field_name;
new_options_label:=:NEW.options_label;
--new_option_mapping:=:NEW.options_mapping; --TODO: add this feature later
new_option_value:=:NEW.option_value;
update metadata set
xml_string=(UPDATEXML(XMLTYPE(xml_string),
'/metadata/fields/field[@name=''' || field_name || ''']/option[@value=''' || new_option_value || ''']/text()',
new_options_label)).getclobval() --must convert to clob as it's stored in the database that way
WHERE
id =(select metadata_id from spaces where prefix_code = space_prefix_code);
DBMS_OUTPUT.put_line(CHR(9) || TO_CHAR(SQL%ROWCOUNT)||' rows updated');
END;
/
来源：https://stackoverflow.com/questions/25531201/selecting-from-and-inserting-to-complex-oracle-xmltype-data