解析XML在PL/SQL查詢屬性

Question

請檢查下面列出XML在PL/SQL的下方，輸出應該是這樣的：

CITY_NAME POPULATION 
MUMBAI 6780000 
DELHI 5100000 
HYDERABAD 2480000 
CHENNAI 6100000 

我使用下面的查詢，但有沒有更好的方式來處理，而不是加入rownum。我承認XML格式可以更好地處理XML屬性。

WITH t as (select XMLTYPE(' 
<ROOT> 
    <CITY_INFO> 
     <CITY> 
      <CITY_NAME Value="MUMBAI"/> 
      <POPULATION Value="6780000" OldValue=""/> 
     </CITY> 
     <CITY> 
      <CITY_NAME Value="DELHI"/> 
      <POPULATION Value="5100000" OldValue=""/> 
     </CITY> 
    </CITY_INFO> 
    <CITY_INFO> 
     <CITY> 
      <CITY_NAME Value="HYDERABAD"/> 
      <POPULATION Value="2480000" OldValue=""/> 
     </CITY> 
     <CITY> 
      <CITY_NAME Value="CHENNAI"/> 
      <POPULATION Value="6100000" OldValue=""/> 
     </CITY> 
    </CITY_INFO> 
</ROOT> 
') as xml from dual) 
select a.CITY_NAME, b.population from (select c.*, rownum as row_num 
from t 
      ,XMLTABLE('/ROOT/CITY_INFO/CITY/CITY_NAME' 
       PASSING t.xml 
       COLUMNS CITY_NAME VARCHAR2(100) PATH '/CITY_NAME/@Value' 
      ) c) a, 
      (select pop.*, rownum as row_num 
      from t 
      ,XMLTABLE('/ROOT/CITY_INFO/CITY/POPULATION' 
       PASSING t.xml 
       COLUMNS POPULATION NUMBER PATH '/POPULATION/@Value' 
      ) pop) b where a.row_num = b.row_num 

Answer 1

由CITY_NAME和POPULATION節點之前在XMLTABLE改變「根路徑」是的水平，並通過//引用CITY_NAME和POPULATION節點，下面的工作對我來說：

WITH t as (select XMLTYPE(' 
<ROOT> 
    <CITY_INFO> 
     <CITY> 
      <CITY_NAME Value="MUMBAI"/> 
      <POPULATION Value="6780000" OldValue=""/> 
     </CITY> 
     <CITY> 
      <CITY_NAME Value="DELHI"/> 
      <POPULATION Value="5100000" OldValue=""/> 
     </CITY> 
    </CITY_INFO> 
    <CITY_INFO> 
     <CITY> 
      <CITY_NAME Value="HYDERABAD"/> 
      <POPULATION Value="2480000" OldValue=""/> 
     </CITY> 
     <CITY> 
      <CITY_NAME Value="CHENNAI"/> 
      <POPULATION Value="6100000" OldValue=""/> 
     </CITY> 
    </CITY_INFO> 
</ROOT> 
') as xml from dual) 
select a.CITY_NAME, a.population 
from t, 
     XMLTABLE('/ROOT/CITY_INFO/CITY' 
       PASSING t.xml 
       COLUMNS CITY_NAME VARCHAR2(100) PATH '//CITY_NAME/@Value', 
       POPULATION NUMBER PATH '//POPULATION/@Value' 
      ) a; 

CITY_NAME   POPULATION 
-------------------- ---------- 
MUMBAI     6780000 
DELHI     5100000 
HYDERABAD    2480000 
CHENNAI     6100000