如何通过在 oracle 中过滤节点来更新 xml？

Question

我在 xml 中有元素列表，如下所示

<Lists>
<Lists>
<list>
<Gender>Male</Gender>
<GenderCode>X</GenderCode>
</list>
<list>
<Gender>Female</Gender>
<GenderCode>X</GenderCode>
</list>
</Lists>

这里我需要根据 Gender 的值更新 GenderCode 值。假设如果 Gender 有“Male”，那么我需要将 GenderCode 更新为“M”。对于“女性”，它应该是“F”。有没有办法单独过滤男性列表并将男性列表的所有 GenderCode 更新为“M”，然后单独过滤女性并将 GenderCode 更新为“F”。有人可以在 oracle PL/SQL 或 Java 中提供建议吗？

Answer 1

您可以使用 XQuery 更新并将代码设置为完整值的第一个字符（假设这不是一个过度设计的示例）；使用静态字符串：

select xmlquery (
  'copy $n := $o
   modify (
     for $g in $n/Lists/list
     return replace value of node $g/GenderCode with fn:substring($g/Gender, 1, 1)
   )
   return $n'
  passing xmltype('<Lists>
<list>
<Gender>Male</Gender>
<GenderCode>X</GenderCode>
</list>
<list>
<Gender>Female</Gender>
<GenderCode>X</GenderCode>
</list>
</Lists>') as "o"
  returning content)
from dual;

XMLQUERY('COPY$N:=$OMODIFY(FOR$GIN$N/LISTS/LISTRETURNREPLACEVALUEOFNODE$G/GENDER
--------------------------------------------------------------------------------
<Lists><list><Gender>Male</Gender><GenderCode>M</GenderCode></list><list><Gender
>Female</Gender><GenderCode>F</GenderCode></list></Lists>

或者可能更有用的是，将存储在表中的值更新为 XMLType：

-- create and populate dummy table
create table your_table (xml_column) as
select xmltype('<Lists>
<list>
<Gender>Male</Gender>
<GenderCode>X</GenderCode>
</list>
<list>
<Gender>Female</Gender>
<GenderCode>X</GenderCode>
</list>
</Lists>')
from dual;

update your_table
set xml_column = xmlquery (
  'copy $n := $o
   modify (
     for $g in $n/Lists/list
     return replace value of node $g/GenderCode with fn:substring($g/Gender, 1, 1)
   )
   return $n'
  passing xml_column as "o"
  returning content
);

1 row updated.

如果您的等效 xml_column 实际上存储为 varchar2 或 CLOB，那么只需将其包装起来：

  passing xmltype(xml_column) as "o"

然后你可以看到值已经按照你想要的方式更新了：

select xml_column from your_table;

XML_COLUMN                                                                      
--------------------------------------------------------------------------------
<Lists>
  <list>
    <Gender>Male</Gender>
    <GenderCode>M</GenderCode>
  </list>
  <list>
    <Gender>Female</Gender>
    <GenderCode>F</GenderCode>
  </list>
</Lists>

---

如果需要从不同的表中查找代码，您可以使用fn:collection with oradb 从 XMLQuery 中访问表：

-- undo previous update to go back to X codes
rollback;

-- look-up table
create table genders (gender, gendercode) as
select 'Male', 'M' from dual
union all
select 'Female', 'F' from dual;

update your_table
set xml_column = xmlquery (
  'copy $n := $o
   modify (
     for $g in $n/Lists/list, $c in fn:collection("oradb:/YOUR_SCHEMA/GENDERS")
       where $c/ROW/GENDER = $g/Gender
       return replace value of node $g/GenderCode with $c/ROW/GENDERCODE
   )
   return $n'
  passing xml_column as "o"
  returning content
);

1 row updated.

得到相同的结果：

select xml_column from your_table;

XML_COLUMN                                                                      
--------------------------------------------------------------------------------
<Lists>
  <list>
    <Gender>Male</Gender>
    <GenderCode>M</GenderCode>
  </list>
  <list>
    <Gender>Female</Gender>
    <GenderCode>F</GenderCode>
  </list>
</Lists>