從XMLType中提取值列

當我遇到以下問題時，我正在學習XMLType應用程序。它將返回CD標題的NULL內容。我不確定它爲什麼會這樣做。從XMLType中提取值列

DROP TABLE Xml_tab; 
/
CREATE TABLE Xml_tab (xmlval xmltype); 
/
INSERT INTO Xml_tab 
VALUES(XMLTYPE.CREATEXML(
    '<CATALOG><CD><TITLE>Empire Burlesque</TITLE><ARTIST>Bob Dylan</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>Columbia</COMPANY><PRICE>10.90</PRICE><YEAR>1985</YEAR></CD><CD><TITLE>Hide your heart</TITLE><ARTIST>Bonnie Tyler</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>CBS Records</COMPANY><PRICE>9.90</PRICE><YEAR>1988</YEAR></CD><CD><TITLE>Greatest Hits</TITLE><ARTIST>Dolly Parton</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>RCA</COMPANY><PRICE>9.90</PRICE><YEAR>1982</YEAR></CD><CD><TITLE>Still got the blues</TITLE><ARTIST>Gary Moore</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Virgin records</COMPANY><PRICE>10.20</PRICE><YEAR>1990</YEAR></CD><CD><TITLE>Eros</TITLE><ARTIST>Eros Ramazzotti</ARTIST><COUNTRY>EU</COUNTRY><COMPANY>BMG</COMPANY><PRICE>9.90</PRICE><YEAR>1997</YEAR></CD><CD><TITLE>One night only</TITLE><ARTIST>Bee Gees</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Polydor</COMPANY><PRICE>10.90</PRICE><YEAR>1998</YEAR></CD><CD><TITLE>Sylvias Mother</TITLE><ARTIST>Dr.Hook</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>CBS</COMPANY><PRICE>8.10</PRICE><YEAR>1973</YEAR></CD><CD><TITLE>Maggie May</TITLE><ARTIST>Rod Stewart</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Pickwick</COMPANY><PRICE>8.50</PRICE><YEAR>1990</YEAR></CD><CD><TITLE>Romanza</TITLE><ARTIST>Andrea Bocelli</ARTIST><COUNTRY>EU</COUNTRY><COMPANY>Polydor</COMPANY><PRICE>10.80</PRICE><YEAR>1996</YEAR></CD><CD><TITLE>When a man loves a woman</TITLE><ARTIST>Percy Sledge</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>Atlantic</COMPANY><PRICE>8.70</PRICE><YEAR>1987</YEAR></CD><CD><TITLE>Black angel</TITLE><ARTIST>Savage Rose</ARTIST><COUNTRY>EU</COUNTRY><COMPANY>Mega</COMPANY><PRICE>10.90</PRICE><YEAR>1995</YEAR></CD><CD><TITLE>1999 Grammy Nominees</TITLE><ARTIST>Many</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>Grammy</COMPANY><PRICE>10.20</PRICE><YEAR>1999</YEAR></CD><CD><TITLE>For the good times</TITLE><ARTIST>Kenny Rogers</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Mucik Master</COMPANY><PRICE>8.70</PRICE><YEAR>1995</YEAR></CD><CD><TITLE>Big Willie style</TITLE><ARTIST>Will Smith</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>Columbia</COMPANY><PRICE>9.90</PRICE><YEAR>1997</YEAR></CD><CD><TITLE>Tupelo Honey</TITLE><ARTIST>Van Morrison</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Polydor</COMPANY><PRICE>8.20</PRICE><YEAR>1971</YEAR></CD><CD><TITLE>Soulsville</TITLE><ARTIST>Jorn Hoel</ARTIST><COUNTRY>Norway</COUNTRY><COMPANY>WEA</COMPANY><PRICE>7.90</PRICE><YEAR>1996</YEAR></CD><CD><TITLE>The very best of</TITLE><ARTIST>Cat Stevens</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Island</COMPANY><PRICE>8.90</PRICE><YEAR>1990</YEAR></CD><CD><TITLE>Stop</TITLE><ARTIST>Sam Brown</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>A and M</COMPANY><PRICE>8.90</PRICE><YEAR>1988</YEAR></CD><CD><TITLE>Bridge of Spies</TITLE><ARTIST>T''Pau</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Siren</COMPANY><PRICE>7.90</PRICE><YEAR>1987</YEAR></CD><CD><TITLE>Private Dancer</TITLE><ARTIST>Tina Turner</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>Capitol</COMPANY><PRICE>8.90</PRICE><YEAR>1983</YEAR></CD><CD><TITLE>Midt om natten</TITLE><ARTIST>Kim Larsen</ARTIST><COUNTRY>EU</COUNTRY><COMPANY>Medley</COMPANY><PRICE>7.80</PRICE><YEAR>1983</YEAR></CD><CD><TITLE>Pavarotti Gala Concert</TITLE><ARTIST>Luciano Pavarotti</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>DECCA</COMPANY><PRICE>9.90</PRICE><YEAR>1991</YEAR></CD><CD><TITLE>The dock of the bay</TITLE><ARTIST>Otis Redding</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>Atlantic</COMPANY><PRICE>7.90</PRICE><YEAR>1987</YEAR></CD><CD><TITLE>Picture book</TITLE><ARTIST>Simply Red</ARTIST><COUNTRY>EU</COUNTRY><COMPANY>Elektra</COMPANY><PRICE>7.20</PRICE><YEAR>1985</YEAR></CD><CD><TITLE>Red</TITLE><ARTIST>The Communards</ARTIST><COUNTRY>UK</COUNTRY><COMPANY>London</COMPANY><PRICE>7.80</PRICE><YEAR>1987</YEAR></CD><CD><TITLE>Unchain my heart</TITLE><ARTIST>Joe Cocker</ARTIST><COUNTRY>USA</COUNTRY><COMPANY>EMI</COMPANY><PRICE>8.20</PRICE><YEAR>1987</YEAR></CD></CATALOG>')); 
/
    COMMIT; 




SELECT P.xmlval.extract('//CATALOG/CD/TITLE/text()').GETSTRINGVAL AS CD 

FROM Xml_tab P;

任何解釋都非常受歡迎。

來源

2014-03-26 user3446787

這是一個有點混亂，但你能得到的CD標題是這樣的：

SELECT extract(value(b),'//TITLE/text()').getstringval() AS CD 
FROM xml_tab x, 
     TABLE(XMLSEQUENCE(extract(xmlval,'//CATALOG/CD'))) b

您排序的XML轉換成表格，然後再與EXTRACT函數獲取值。

來源

2014-03-26 12:08:04 pablomatico

謝謝。我看到你使用了「// TITLE /」而不是完整路徑。你能告訴我什麼是「//」的用法嗎 – user3446787

來自Oracle文檔的引用：「//」用於標識當前節點的所有後代。例如，PO // ZIP匹配「PO」元素下的任何郵政編碼元素。 – pablomatico

感謝您的解釋！我還有一個問題..你能告訴我爲什麼下面的查詢不工作:(它可能是很基本的，但如果你能幫助我.. DECLARE l_xml的XMLType。 BEGIN SELECT SYS_XMLAGG（XMLELEMENT（「EMP」，xmlforest（e.employee_id，e.first_name，e.last_name，e.salary））） INTO l_xml FROM employees e; SELECT extract（l_xml，'// employee_id/text（）'）。getStringVal（）AS EMPNO，提取物（l_xml， '//如first_name /文本（）'）。getStringVal（）AS的ename，提取物（l_xml， '//工資/文本（）'）。getStringVal（）AS SAL FROM dual; END; 預計INTO子句 – user3446787

從XMLType中提取值列

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