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<library>
<items>
<book asin="0201100886"
created="128135928"
lastLookupTime="128135928">
<uuid>BA57A934-6CDC-11D9-830B-000393D3DE16</uuid>
<title>Compilers</title>
<authors>
<author>Alfred V. Aho</author>
<author>Ravi Sethi</author>
<author>Jeffrey D. Ullman</author>
</authors>
<publisher>Addison Wesley</publisher>
<published>1986-01-01</published>
<price>102.00</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0122513363" created="128135600" lastLookupTime="128136224">
<uuid>F7468E09-6CDB-11D9-830B-000393D3DE16</uuid>
<title>Database Driven Web Sites</title>
<authors><author>Jesse Feiler</author></authors>
<publisher>Morgan Kaufmann</publisher>
<published>1998-04-15</published>
<edition>Paperback</edition>
<price>50.95</price>
<purchaseDate>2005-01-22</purchaseDate>
<currentValue>35.00</currentValue>
<netRating>1.5</netRating>
<genres>
<genre>Computer Bks - Internet</genre>
<genre>Computer Books: Web Programming</genre>
<genre>Computer Networks</genre>
<genre>Computers</genre>
<genre>Database Management - General</genre>
<genre>Database management</genre>
<genre>Design</genre>
<genre>Distributed Databases</genre>
<genre>Information Technology</genre>
<genre>Internet - Web Site Design</genre>
<genre>Networking - General</genre>
<genre>Web sites</genre>
<genre>Computers / Computer Science</genre>
</genres>
<upc>608628133638</upc>
</book>
<book asin="0201441241"
created="128136896"
lastLookupTime="128136896">
<uuid>FBC45DF4-6CDE-11D9-830B-000393D3DE16</uuid>
<title>Introduction to Automata Theory, Languages, and Computation (2nd Edition)</title>
<authors>
<author>John E. Hopcroft</author>
<author>Rajeev Motwani</author>
<author>Jeffrey D. Ullman</author>
</authors>
<publisher>Addison Wesley</publisher>
<published>2000-11-14</published>
<price>108.20</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0471250600"
created="128136896"
lastLookupTime="128136896">
<uuid>FBC7CA56-6CDE-11D9-830B-000393D3DE16</uuid>
<title>Operating System Concepts</title>
<authors>
<author>Abraham Silberschatz</author>
<author>Greg Gagne</author>
<author>Peter Baer Galvin</author>
</authors>
<publisher>Wiley</publisher>
<published>2002-03-08</published>
<price>107.95</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0321193628"
created="128136896"
lastLookupTime="128136896">
<uuid>FBCB3DCF-6CDE-11D9-830B-000393D3DE16</uuid>
<title>Concepts of Programming Languages, Sixth Edition</title>
<authors><author>Robert W. Sebesta</author></authors>
<publisher>Addison Wesley</publisher>
<published>2003-07-24</published>
<price>112.40</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0138613370" created="128136944" lastLookupTime="128136944">
<uuid>19E5E602-6CDF-11D9-830B-000393D3DE16</uuid>
<title>First Course in Database Systems, A</title>
<authors>
<author>Jeffrey D. Ullman</author>
<author>Jennifer Widom</author>
</authors>
<publisher>Prentice Hall</publisher>
<published>1997-04-02</published>
<edition>Hardcover</edition>
<price>67.00</price>
<purchaseDate>2005-01-22</purchaseDate>
<netRating>3.2</netRating>
<genres>
<genre>Computer Books: Database</genre>
<genre>Computers</genre>
<genre>Database Engineering</genre>
<genre>Database Management - General</genre>
<genre>Database management</genre>
</genres>
<recommendations>
<book asin="0130402648"
created="128136952"
lastLookupTime="128136952">
<uuid>1C60074A-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Database System Implementation</title>
<authors>
<author>Hector Garcia-Molina</author>
<author>Jeffrey D. Ullman</author>
<author>Jennifer D. Widom</author>
</authors>
<publisher>Prentice Hall</publisher>
<published>1999-06-11</published>
<price>89.00</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0130319953"
created="128136952"
lastLookupTime="128136952">
<uuid>1C635DB0-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Database Systems: The Complete Book</title>
<authors>
<author>Hector Garcia-Molina</author>
<author>Jeffrey D. Ullman</author>
<author>Jennifer D. Widom</author>
</authors>
<publisher>Prentice Hall</publisher>
<published>2001-10-02</published>
<price>98.00</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0201976994"
created="128136952"
lastLookupTime="128136952">
<uuid>1C66B7B4-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Computer Networking: A Top-Down Approach Featuring the Internet</title>
<authors>
<author>James F. Kurose</author>
<author>Keith W. Ross</author>
<author>James Kurose</author>
<author>Keith Ross</author>
</authors>
<publisher>Addison Wesley</publisher>
<published>2002-07-17</published>
<price>100.00</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0131433512"
created="128136952"
lastLookupTime="128136952">
<uuid>1C6AC88C-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Computer Networks and Internets, Fourth Edition</title>
<authors>
<author>Douglas E Comer</author>
<author>Ralph E. Droms</author>
</authors>
<publisher>Prentice Hall</publisher>
<published>2003-07-28</published>
<price>100.00</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0262062178"
created="128136952"
lastLookupTime="128136952">
<uuid>1C6E712C-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Essentials of Programming Languages - 2nd Edition</title>
<authors>
<author>Daniel P. Friedman</author>
<author>Mitchell Wand</author>
<author>Christopher T. Haynes</author>
</authors>
<publisher>The MIT Press</publisher>
<published>2001-01-29</published>
<price>62.00</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0471250600"
created="128136952"
lastLookupTime="128136952">
<uuid>1C71B23E-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Operating System Concepts</title>
<authors>
<author>Abraham Silberschatz</author>
<author>Greg Gagne</author>
<author>Peter Baer Galvin</author>
</authors>
<publisher>Wiley</publisher>
<published>2002-03-08</published>
<price>107.95</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0137903952"
created="128136952"
lastLookupTime="128136952">
<uuid>1C764AD4-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Artificial Intelligence: A Modern Approach (2nd Edition)</title>
<authors>
<author>Stuart J. Russell</author>
<author>Peter Norvig</author>
</authors>
<publisher>Prentice Hall</publisher>
<published>2002-12-20</published>
<price>93.33</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="155860832X"
created="128136952"
lastLookupTime="128136952">
<uuid>1C898640-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Computer Networks: A Systems Approach, 3rd Edition</title>
<authors>
<author>Larry L. Peterson</author>
<author>Bruce S. Davie</author>
</authors>
<publisher>Morgan Kaufmann</publisher>
<published>2003-05-22</published>
<price>89.95</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0130669474"
created="128136952"
lastLookupTime="128136952">
<uuid>1C8DD37A-6CDF-11D9-830B-000393D3DE16</uuid>
<title>SQL Fundamentals (2nd Edition)</title>
<authors><author>John J. Patrick</author></authors>
<publisher>Prentice Hall PTR</publisher>
<published>2002-05-07</published>
<price>54.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0321122267"
created="128136952"
lastLookupTime="128136952">
<uuid>1C91D772-6CDF-11D9-830B-000393D3DE16</uuid>
<title>Fundamentals of Database Systems, Fourth Edition</title>
<authors>
<author>Ramez Elmasri</author>
<author>Shamkant B. Navathe</author>
</authors>
<publisher>Addison Wesley</publisher>
<published>2003-07-23</published>
<price>104.20</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
</recommendations>
</book>
<book asin="1558604820" created="128136024" lastLookupTime="128136024">
<uuid>F3C7B24F-6CDC-11D9-830B-000393D3DE16</uuid>
<title>A Complete Guide to DB2 Universal Database</title>
<authors>
<author>D. D. Chamberlin</author>
<author>Don Chamberlin</author>
</authors>
<publisher>Morgan Kaufmann</publisher>
<published>1998-08-15</published>
<edition>Paperback</edition>
<price>62.95</price>
<purchaseDate>2005-01-22</purchaseDate>
<netRating>4.4</netRating>
<genres>
<genre>Computer Bks - Data Base Management</genre>
<genre>Computer Books: Database</genre>
<genre>Computers</genre>
<genre>Database Management - General</genre>
<genre>General</genre>
<genre>IBM Database 2</genre>
<genre>Information Storage & Retrieval</genre>
<genre>Relational Databases</genre>
<genre>Computers / Information Storage & Retrieval</genre>
</genres>
<recommendations>
<book asin="0072133449"
created="128136024"
lastLookupTime="128136024">
<uuid>F6B35F21-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2: The Complete Reference (Complete Reference Series)</title>
<authors>
<author>Roman B. Melnyk</author>
<author>Paul C. Zikopoulos</author>
</authors>
<publisher>McGraw-Hill Companies</publisher>
<published>2001-10-01</published>
<price>59.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0130661112"
created="128136024"
lastLookupTime="128136024">
<uuid>F6B97E54-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 UDB v8 Handbook for Windows and UNIX/Linux</title>
<authors><author>Philip K. Gunning</author></authors>
<publisher>Prentice Hall PTR</publisher>
<published>2003-08-06</published>
<price>59.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0131007726"
created="128136024"
lastLookupTime="128136024">
<uuid>F6BCBB88-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 SQL Procedural Language for Linux, Unix and Windows</title>
<authors>
<author>Paul Yip</author>
<author>Drew Bradstock</author>
<author>Hana Curtis</author>
<author>Michael Gao</author>
<author>Zamil Janmohamed</author>
<author>Clara Liu</author>
<author>Fraser McArthur</author>
</authors>
<publisher>Prentice Hall PTR</publisher>
<published>2002-12-24</published>
<price>59.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0131424653"
created="128136024"
lastLookupTime="128136024">
<uuid>F6C0A296-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 UDB V8.1 Certification Exam 700 Study Guide</title>
<authors><author>Roger E. Sanders</author></authors>
<publisher>Prentice Hall PTR</publisher>
<published>2003-09-17</published>
<price>49.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0764508415"
created="128136024"
lastLookupTime="128136024">
<uuid>F6C4058C-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 Fundamentals Certification for Dummies</title>
<authors>
<author>Paul C. Zikopoulos</author>
<author>Jennifer Gibbs</author>
<author>Roman B. Melnyk</author>
</authors>
<publisher>For Dummies</publisher>
<published>2001-08-01</published>
<price>34.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0130463612"
created="128136024"
lastLookupTime="128136024">
<uuid>F6D9A3D8-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 Universal Database V8 for Linux, UNIX, and Windows Database Administration Certification Guide (5th Edition)</title>
<authors>
<author>George Baklarz</author>
<author>Bill Wong</author>
</authors>
<publisher>Prentice Hall PTR</publisher>
<published>2003-02-10</published>
<price>59.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0130463884"
created="128136024"
lastLookupTime="128136024">
<uuid>F6DDBAB9-6CDC-11D9-830B-000393D3DE16</uuid>
<title>Advanced DBA Certification Guide and Reference for DB2 UDB v8 for Linux, Unix and Windows</title>
<authors>
<author>Dwaine R. Snow</author>
<author>Thomas Xuan Phan</author>
<author>Dwaine Snow</author>
</authors>
<publisher>Prentice Hall PTR</publisher>
<published>2003-07-07</published>
<price>59.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="155860443X"
created="128136024"
lastLookupTime="128136024">
<uuid>F6E1063D-6CDC-11D9-830B-000393D3DE16</uuid>
<title>Advanced Database Systems (The Morgan Kaufmann Series in Data Management Systems)</title>
<authors>
<author>Carlo Zaniolo</author>
<author>Stefano Ceri</author>
<author>Christos Faloutsos</author>
<author>Richard T. Snodgrass</author>
<author>V. S. Subrahmanian</author>
<author>Roberto Zicari</author>
</authors>
<publisher>Morgan Kaufmann</publisher>
<published>1997-05-01</published>
<price>88.95</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0131840487"
created="128136024"
lastLookupTime="128136024">
<uuid>F6E441CE-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 UDB V8.1 Certification Exams 701 and 706 Study Guide</title>
<authors><author>Roger E. Sanders</author></authors>
<publisher>Prentice Hall PTR</publisher>
<published>2003-12-12</published>
<price>49.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
<book asin="0132037955"
created="128136024"
lastLookupTime="128136024">
<uuid>F6E77C2C-6CDC-11D9-830B-000393D3DE16</uuid>
<title>DB2 High Performance Design and Tuning</title>
<authors>
<author>Richard Yevich</author>
<author>Susan Lawson</author>
<author>Richard A. Yevich</author>
</authors>
<publisher>Prentice Hall PTR</publisher>
<published>2000-08-24</published>
<price>54.99</price>
<purchaseDate>2005-01-22</purchaseDate>
</book>
</recommendations>
</book>
</items>
<borrowers>
<borrower id="1">
<name> John Doe </name>
<phone> 555-1212 </phone>
<borrowed>
<book asin="0138613370"/>
<book asin="0122513363"/>
</borrowed>
</borrower>
<borrower id="2">
<name> Mary Jane </name>
<phone> 555-1213 </phone>
<borrowed>
<book asin="0201100886"/>
<book asin="0122513363"/>
</borrowed>
</borrower>
<borrower id="3">
<name> Bill Jones </name>
<phone> 555-1312 </phone>
<borrowed />
</borrower>
<borrower id="4">
<name> Anne Marie</name>
<phone> 555-1314</phone>
<borrowed>
<book asin="0138613370"/>
<book asin="0201100886"/>
<book asin="0122513363"/>
<book asin="1558604820"/>
</borrowed>
</borrower>
</borrowers>
</library>
我需要归还所有借书的人，他们的名字和书名。
这是我的xQuery：
xquery version "1.0";
for $library in doc("library.xml")/library
for $book in $library/items/book
let $borrowed := $library/borrowers/borrower
return
<borrower>
<name>
{data($borrowed/name)}
</name>
<title>
{data($book[@asin = $borrowed//book/@asin]/title)}
</title>
</borrower>
以下是它的回报：
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title>Compilers</title>
</borrower>
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title>Database Driven Web Sites</title>
</borrower>
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title/>
</borrower>
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title/>
</borrower>
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title/>
</borrower>
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title>First Course in Database Systems, A</title>
</borrower>
<borrower>
<name> John Doe Mary Jane Bill Jones Anne Marie</name>
<title>A Complete Guide to DB2 Universal Database</title>
</borrower>
首先，错误的是它返回了所有借用书而不是每个标签一个名字的人的名字。 其次，它应该归还8本书，而且只返回7本。
任何人都可以帮我理解我的xQuery ????
有什么问题答案 0 :(得分：0)
我没有使用XQuery的经验，但据我所知，您的谓词[@asin = $borrowed//book/@asin]应该移到let语句中，否则没有连接，$ book和$之间没有链接借来的。由于你已经在$ book中有一本特定的书，因此在返回书名时不需要谓词。
答案 1 :(得分：0)
我非常确定你试图获得每个借款人的清单以及他们借来的书籍的标题。您的XQuery的问题在于您正在迭代每个/library/items/book而不是每个借用者。此外，您的示例中只有/library/items/book;不是8。
这个XQuery应该做你想做的事。
<强>的XQuery
<borrowers>
{
let $library := doc('library.xml')
for $borrower in $library/library/borrowers/borrower
let $name := $borrower/name
let $asins := data($borrower/borrowed/book/@asin)
let $titles :=
for $asin in $asins
return $library/library/items/book[@asin = $asin]/title
return
<borrower>
{$name}
{$titles}
</borrower>
}
</borrowers>
<强>结果
<borrowers>
<borrower>
<name> John Doe </name>
<title>First Course in Database Systems, A</title>
<title>Database Driven Web Sites</title>
</borrower>
<borrower>
<name> Mary Jane </name>
<title>Compilers</title>
<title>Database Driven Web Sites</title>
</borrower>
<borrower>
<name> Bill Jones </name>
</borrower>
<borrower>
<name> Anne Marie</name>
<title>First Course in Database Systems, A</title>
<title>Compilers</title>
<title>Database Driven Web Sites</title>
<title>A Complete Guide to DB2 Universal Database</title>
</borrower>
</borrowers>