如何在Oralce中生成包含表和/或列COMMENT的XML？

Question

需要使用表和comlumns注释列表生成XML。

SELECT * FROM USER_TAB_COMMENTS; -- my tables

| TABLE_NAME | TABLE_TYPE | COMMENT     |
-----------------------------------------
| table_a    | TABLE      | t.A comment |
| table_b    | TABLE      | t.B comment |


SELECT * FROM USER_TAB_COMMENTS; -- my comments

| TABLE_NAME | COLUMN_NAME | COMMENT      |
-------------------------------------------
| table_a    | col_1       | c.A1 comment |
| table_a    | col_2       | c.A2 comment |
| table_b    | col_1       | c.B1 comment |
| table_b    | col_2       | c.B2 comment |

表格的XML描述，我需要：

SELECT DBMS_METADATA.GET_XML(REPLACE(OBJECT_TYPE, ' ', '_'), OBJECT_NAME) xml
FROM USER_OBJECTS
WHERE OBJECT_TYPE IN ('TABLE');

问题是：如何为我的评论获得等效的XML？

SELECT DBMS_METADATA.GET_XML('COMMENT', TABLE_NAME) xml
FROM USER_TAB_COMMENTS; -- doesn't work

致以最诚挚的问候和感谢帮助。

Answer 1

每个项目获得一行：

SELECT XMLELEMENT(
         "TABLE",
         XMLFOREST(
           table_name,
           table_type,
           comments
         )
       ).getClobVal() As xml
FROM   user_tab_comments;

使用嵌套在其中的所有XML获取一行：

SELECT XMLELEMENT(
         "TABLES",
         XMLAGG(
           XMLELEMENT(
             "TABLE",
             XMLFOREST(
               table_name,
               table_type,
               comments
             )
           )
         )
       ).getClobVal() As xml
FROM   user_tab_comments;