Oracle操作XML各种场景介绍(一)

一 如何生成XML文件：

1、使用dbms_xmlquery和utl_file内置包（scott用户执行）

CREATE OR REPLACE DIRECTORY xml_dir AS 'd:\app\xml';

DROP SEQUENCE seq_filename;
CREATE SEQUENCE seq_filename
MINVALUE 10000
MAXVALUE 99999
INCREMENT BY 1
START WITH 10000
NOCYCLE;

DECLARE
v_filename Varchar2(50) := 'Empmsg'||to_char(seq_filename.nextval)||'.xml';
xml_str clob;
xml_file utl_file.file_type;
offset number;
buffer varchar2(32767);
buffer_size number;
BEGIN
offset := 1;
buffer_size := 3000;
xml_file := utl_file.fopen('XML_DIR', v_filename, 'w');
xml_str := dbms_xmlquery.getxml('select empno,
ename,
job,
mgr,
hiredate,
sal,
comm,
deptno
from emp');

while (offset < dbms_lob.getlength(xml_str)) loop
buffer := dbms_lob.substr(xml_str, buffer_size, offset);
utl_file.put(xml_file, buffer);
utl_file.fflush(xml_file);
offset := offset + buffer_size;
end loop;

utl_file.fclose(xml_file);
END;

2、使用XMLELEMENT系列内置函数返回xml（sys用户执行）

DECLARE
v_filename Varchar2(50) := 'Empmsg'||to_char(scott.seq_filename.nextval)||'.xml';
xml_str clob;
xml_file utl_file.file_type;
offset number;
buffer varchar2(32767);
buffer_size number;
BEGIN
offset := 1;
buffer_size := 3000;
xml_file := utl_file.fopen('XML_DIR', v_filename, 'w');
SELECT XMLElement("DEPARTMENT"
, XMLAttributes( department_id as "ID"
, department_name as "NAME"
)
, XMLElement("EMPLOYEES"
, (SELECT XMLAgg( XMLElement("EMPLOYEE"
, XMLForest(employee_id as "ID"
,first_name||' '||last_name as "NAME"
)
)
)
FROM hr.employees emp
WHERE emp.department_id = dept.department_id
)
)
).getclobval() INTO xml_str
FROM hr.departments dept
WHERE department_id = 20;

while (offset < dbms_lob.getlength(xml_str)) loop
buffer := dbms_lob.substr(xml_str, buffer_size, offset);
utl_file.put(xml_file, buffer);
utl_file.fflush(xml_file);
offset := offset + buffer_size;
end loop;

utl_file.fclose(xml_file);
END;

--XMLElement: 将一个关系值转换为XML元素的函数，格式为值

--XMLAttributes: 用于在SQL查询返回的 XML 元素中设置属性的函数

--XMLForest: 该函数返回一个或多个子元素的集合,该函数使用列名做为XML元素的名称并用SQL值表达式做为XML元素的内容，但使用时不能指定元素的属性

--XMLAgg: 在GROUP BY查询中对XML数据进行分组或汇总的函数

PS: 使用SPOOL方式导出文件：

SET TRIMSPOOL ON
SET TERMOUT ON
SET FEEDBACK OFF
SET VERIFY OFF
SET ECHO OFF
SET PAGESIZE 999
SET HEAD OFF
SET HEADING OFF
SET LONG 5000
spool c:\a.xml
SELECT XMLElement("DEPARTMENT"
, XMLAttributes( department_id as "ID"
, department_name as "NAME"
)
, XMLElement("EMPLOYEES"
, (SELECT XMLAgg( XMLElement("EMPLOYEE"
, XMLForest(employee_id as "ID"
,first_name||' '||last_name as "NAME"
)
)
)
FROM employees emp
WHERE emp.department_id = dept.department_id