查詢XMLType列

Question

可以說我有一個表作爲以下結構：

創建表溫度（ID數字，數據的XMLType）;

和ID 1內容

<PivotSet> 
<item> 
    <column name = "ATTRIBUTENAME">test</column> 
    <column name = "MAX(ATTRIBUTEVALUE)">testVal</column> 
</item> 
<item> 
    <column name = "ATTRIBUTENAME">test1</column> 
    <column name = "MAX(ATTRIBUTEVALUE)">test1Val</column> 
</item> 
<item> 
    <column name = "ATTRIBUTENAME">test2</column> 
    <column name = "MAX(ATTRIBUTEVALUE)">test2Val</column> 
</item> 

現在我一直渴望實現的是扁平化在XML中的元素，得到這個結果：

id | test | test 1 | test 2 | 
    1 |testval |testval1 |testval2 | 

所以我想要的是每個項目顯示有第一個<column>爲columnName，第二個作爲該列的值。

Answer 1

SQL> select * from t; 

     ID                  
----------                  
DATA                    
-------------------------------------------------------------------------------- 
     1                  
<PivotSet>                  
    <item>                   
    <column name="ATTRIBUTENAME">test</column>         
    <column name="MAX(ATTRIBUTEVALUE)">testVal</column>       
    </item>                  
    <item>                   
    <column name="ATTRIBUTENAME">test1</column>         
    <column name="MAX(ATTRIBUTEVALUE)">test1Val</column>       
    </item>                  
    <item>                   
    <column name="ATTRIBUTENAME">test2</column>         
    <column name="MAX(ATTRIBUTEVALUE)">test2Val</column>       
    </item>                  
</PivotSet>  

SQL> select 'ID' cn, 
    2 max(decode(rn,1,column_name,null)) a, 
    3 max(decode(rn,2,column_name,null)) b, 
    4 max(decode(rn,3,column_name,null)) c, 
    5 id, 
    6 max(decode(rn,1,value,null)) d, 
    7 max(decode(rn,2,value,null)) e, 
    8 max(decode(rn,3,value,null)) f 
    9 from (
10 select id, extractValue(value(r),'item/column[@name = "ATTRIBUTENAME"]') column_name 
11 , extractValue(value(r),'item/column[@name = "MAX(ATTRIBUTEVALUE)"]') value 
12 , row_number() over(partition by id order by null) rn 
13 from t, 
14 table(XMLSequence((t.data).extract('PivotSet/item'))) r 
15 ) group by id 
16/

CN A  B  C   ID D  E  F       
-- -------- -------- -------- ---- -------- -------- --------     
ID test  test1 test2  1 testVal test1Val test2Val 

或（對於這個問題的新版本）

SQL> select id, a, b, c 
    2 from (
    3 select 'ID' id, max(decode(rn, 1, column_name)) a, max(decode(rn, 2, column_name)) b, max(decode(rn, 3, column_name)) c, 1 s 
    4 from (
    5 select id, extractValue(value(r),'item/column[@name = "ATTRIBUTENAME"]') column_name 
    6 , extractValue(value(r),'item/column[@name = "MAX(ATTRIBUTEVALUE)"]') value 
    7 , row_number() over(partition by id order by null) rn 
    8 from t, 
    9 table(XMLSequence((t.data).extract('PivotSet/item'))) r 
10 ) 
11 group by id 
12 union all 
13 select to_char(id), max(decode(rn, 1, value)), max(decode(rn, 2, value)), max(decode(rn, 3, value)) c, 2 s 
14 from (
15 select id, extractValue(value(r),'item/column[@name = "ATTRIBUTENAME"]') column_name 
16 , extractValue(value(r),'item/column[@name = "MAX(ATTRIBUTEVALUE)"]') value 
17 , row_number() over(partition by id order by null) rn 
18 from t, 
19 table(XMLSequence((t.data).extract('PivotSet/item'))) r 
20 ) 
21 group by id 
22 ) order by id, s 
23/

ID          A  B  C      
---------------------------------------- -------- -------- --------    
ID          test  test1 test2     
1          testVal test1Val test2Val 

（不能使用保條款由於在11.2.3 ORA-00600）