我有以下XML：
<record>
<leader>02220cim a2200325 a 4500</leader>
<datafield tag="035" ind1=" " ind2=" ">
<subfield code="a">P286</subfield>
</datafield>
<datafield tag="100" ind1="1" ind2=" ">
<subfield code="a">Gold, Claudia M.</subfield>
</datafield>
<datafield tag="300" ind1=" " ind2=" ">
<subfield code="a">1 disque son. (6h47) :</subfield>
<subfield code="b">numérique ;</subfield>
<subfield code="c">12 cm.</subfield>
</datafield>
<datafield tag="650" ind1=" " ind2="6">
<subfield code="a">Émotions chez l'enfant</subfield>
</datafield>
<datafield tag="650" ind1=" " ind2="6">
<subfield code="a">Parents et enfants</subfield>
</datafield>
<datafield tag="655" ind1=" " ind2="4">
<subfield code="a">Enregistrement numérique sur CD.</subfield>
</datafield>
<datafield tag="700" ind1="1" ind2=" ">
<subfield code="a">Taussig, Sylvie</subfield>
</datafield>
<datafield tag="700" ind1="1" ind2=" ">
<subfield code="a">Marcelli, Daniel</subfield>
</datafield>
<datafield tag="852" ind1=" " ind2=" ">
<subfield code="a">GBQ</subfield>
<subfield code="b">QO</subfield>
<subfield code="c">DC13378</subfield>
<subfield code="d">32002518936826</subfield>
</datafield>
<datafield tag="852" ind1=" " ind2=" ">
<subfield code="a">GBQ</subfield>
<subfield code="b">QO</subfield>
<subfield code="c">DC13378</subfield>
<subfield code="d">32002518936859</subfield>
</datafield>
</record>
我需要将行中的值转换为列。例如：
leader datafield_035 datafield_100 datafield_300 datafield_650 ...
-----------------------------------------------------------------------
02220...
这是我做的：
1 / Step1：
insert into table_data(leader, tag, subfield)
(
select x.leader,x1.tag, x2.subfield
from table_xml t
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/collection/record'
passing t.xml_document
columns leader VARCHAR2(100) PATH 'leader',
datafield xmltype path './datafield'
) x
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/datafield[@tag=245 or @tag=100 or @tag=300 or @tag=260 or @tag=650
or @tag=520 or @tag=091 or @tag=534 or @tag=245 or @tag=500 or @tag=655 or @tag=505]'
passing x.datafield
columns tag VARCHAR2(20) PATH '@tag',
subfield xmltype PATH './subfield'
)x1
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/subfield'
passing x1.subfield
COLUMNS subfield varchar2(2000) PATH '.'
)x2
where t.id=3
)
;
2 /第2步：
INSERT INTO table_CLOB (leader, tag, subfield)
select leader, tag,
rtrim(xmlagg(XMLELEMENT(e,subfield, ' ; ').extract('//text()')order by subfield).getClobVal(),' ; ') as subfields
from table_data
group by leader, tag
;
3 / Step3：
insert into table_result(leader, tag, subfield)
( select leader, "'091'" as cote, "'100'" as auteur, "'245'" as titre,
"'300'" as Desc_Mater, "'260'" as edition,"'520'" as resume, "'534'" as version,
"'500'" as notes, "'650'" as sujet
from
(
select leader, tag, dbms_lob.substr(subfield,2000,1) as col
from table_clob
)
pivot(max(col) for tag in ('091', '100', '245', '260','650','520','300','534','500'))
);
完成这些步骤后，我得到了我期望的结果，但性能并不是很好。
无论如何，我可以做一次拍摄并获得最终结果吗？
答案 0 :(得分：1)
您可以使用subquery factoring（也称为公用表表达式或CTE）而不是永久（甚至是临时）表。
但是你真的不需要做所有工作，你可以使用listagg()和你的第一个查询：
select x.leader
, listagg(case when x1.tag = '091' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as cote
, listagg(case when x1.tag = '100' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as auteur
, listagg(case when x1.tag = '245' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as titre
, listagg(case when x1.tag = '300' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as desc_mater
, listagg(case when x1.tag = '260' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as edition
, listagg(case when x1.tag = '520' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as resume
, listagg(case when x1.tag = '534' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as version
, listagg(case when x1.tag = '500' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as notes
, listagg(case when x1.tag = '650' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as subjet
from table_xml t
cross join XMLTABLE ( ... ) x
cross join XMLTABLE ( ... )x1
cross join XMLTABLE ( ... )x2
where t.id=3
group by x.leader;
从样本中获得相同的结果;这可能是一件好事。
SQL Fiddle demo;我打算把CTE版本放在那里作为参考，但它正在杀死它 - 它经常对XML或CTE不满意，而且它也在间歇性地与listagg版本斗争;所以这是两者的完整版本：
with table_data as (
select x.leader,x1.tag, x2.subfield
from table_xml t
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/collection/record'
passing t.xml_document
columns leader VARCHAR2(100) PATH 'leader',
datafield xmltype path './datafield'
) x
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/datafield[@tag=245 or @tag=100 or @tag=300 or @tag=260 or @tag=650
or @tag=520 or @tag=091 or @tag=534 or @tag=245 or @tag=500 or @tag=655 or @tag=505]'
passing x.datafield
columns tag VARCHAR2(20) PATH '@tag',
subfield xmltype PATH './subfield'
)x1
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/subfield'
passing x1.subfield
COLUMNS subfield varchar2(2000) PATH '.'
)x2
where t.id=3
),
table_clob as (
select leader, tag,
rtrim(xmlagg(XMLELEMENT(e,subfield, ' ; ').extract('//text()')order by subfield).getClobVal(),' ; ') as subfield
from table_data
group by leader, tag
),
table_result as (
select leader, "'091'" as cote, "'100'" as auteur, "'245'" as titre,
"'300'" as Desc_Mater, "'260'" as edition,"'520'" as resume, "'534'" as version,
"'500'" as notes, "'650'" as sujet
from
(
select leader, tag, dbms_lob.substr(subfield,2000,1) as col
from table_clob
)
pivot(max(col) for tag in ('091', '100', '245', '260','650','520','300','534','500'))
)
select * from table_result;
select x.leader
, listagg(case when x1.tag = '091' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as cote
, listagg(case when x1.tag = '100' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as auteur
, listagg(case when x1.tag = '245' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as titre
, listagg(case when x1.tag = '300' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as desc_mater
, listagg(case when x1.tag = '260' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as edition
, listagg(case when x1.tag = '520' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as resume
, listagg(case when x1.tag = '534' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as version
, listagg(case when x1.tag = '500' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as notes
, listagg(case when x1.tag = '650' then x2.subfield end, ' ; ')
within group (order by x2.subfield) as subjet
from table_xml t
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/collection/record'
passing t.xml_document
columns leader VARCHAR2(100) PATH 'leader',
datafield xmltype path './datafield'
) x
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/datafield[@tag=245 or @tag=100 or @tag=300 or @tag=260 or @tag=650
or @tag=520 or @tag=091 or @tag=534 or @tag=245 or @tag=500 or @tag=655 or @tag=505]'
passing x.datafield
columns tag VARCHAR2(20) PATH '@tag',
subfield xmltype PATH './subfield'
)x1
cross join XMLTABLE (xmlnamespaces (default 'http://www.loc.gov/MARC21/slim')
, '/subfield'
passing x1.subfield
COLUMNS subfield varchar2(2000) PATH '.'
)x2
where t.id=3
group by x.leader;