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j2eePDF格式的电子书

        value="${bookRow[7]}" />

      <c:if test="${item.quantity > inventory.quantity}">
        <c:set var="sufficientInventory" value="false" />
        <h3><font color="red" size="+2">
        <fmt:message key="OrderError"/> 
        There is insufficient inventory for 
        <i>${bookRow[3]}</i>.</font></h3>
      </c:if>
    </c:forEach>
  </c:forEach>

  <c:if test="${sufficientInventory == 'true'}" />
    <c:forEach var="item" items="${sessionScope.cart.items}">
      <c:set var="book" value="${item.item}" />
      <c:set var="bookId" value="${book.bookId}" />

      <sql:query var="books" 
        sql="select * from PUBLIC.books where id = ?" >
        <sql:param value="${bookId}" />
      </sql:query>

      <c:forEach var="bookRow" begin="0"
        items="${books.rows}">            
        <sql:update var="books" sql="update PUBLIC.books set
          inventory = inventory - ? where id = ?" >
          <sql:param value="${item.quantity}" />
          <sql:param value="${bookId}" />
        </sql:update>
      </c:forEach>
    </c:forEach>
    <h3><fmt:message key="ThankYou"/>
      ${param.cardname}.</h3><br>  
  </c:if>
&lt;/sql:transaction&gt;<a name="wp84910"> </a>
</pre></div>
<a name="wp77082"> </a><h3 class="pHeading2">
query Tag Result Interface
</h3>
<a name="wp75351"> </a><p class="pBody">
The <code class="cCode">Result</code> interface is used to retrieve information from objects returned from a <code class="cCode">query</code> tag. 
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
public interface Result
&nbsp;&nbsp;public String[] getColumnNames();
&nbsp;&nbsp;public int getRowCount()
&nbsp;&nbsp;public Map[] getRows();
&nbsp;&nbsp;public Object[][] getRowsByIndex();
&nbsp;&nbsp;public boolean isLimitedByMaxRows();<a name="wp76211"> </a>
</pre></div>
<a name="wp75325"> </a><p class="pBody">
For complete information about this interface, see the API documentation for the <code class="cCode"><a  href="http://java.sun.com/j2ee/1.4/docs/api/index.htmlapi/javax/servlet/jsp/jstl/sql/package-summary.html" target="_blank">javax.servlet.jsp.jstl.sql</a></code> package.
</p>
<a name="wp75363"> </a><p class="pBody">
The <code class="cCode">var</code> attribute set by a <code class="cCode">query</code> tag is of type <code class="cCode">Result</code>. The <code class="cCode">getRows</code> method returns an array of maps that can be supplied to the <code class="cCode">items</code> attribute of a <code class="cCode">forEach</code> tag. The JSTL expression language converts the syntax <code class="cCode">${</code><code class="cVariable">result</code><code class="cCode">.rows}</code> to a call to <code class="cVariable">result</code><code class="cCode">.getRows</code>. The expression <code class="cCode">${books.rows}</code> in the following example returns an array of maps.
</p>
<a name="wp70265"> </a><p class="pBody">
When you provide a array of maps to the <code class="cCode">forEach</code> tag, the <code class="cCode">var</code> attribute set by the tag is of type <code class="cCode">Map</code>. To retrieve information from a row, use the <code class="cCode">get(&quot;</code><code class="cVariable">colname</code><code class="cCode">&quot;)</code> method to get a column value. The JSTL expression language converts the syntax <code class="cCode">${</code><code class="cVariable">map</code><code class="cCode">.</code><code class="cVariable">colname</code><code class="cCode">}</code> to a call to <code class="cVariable">map</code><code class="cCode">.get(&quot;</code><code class="cVariable">colname</code><code class="cCode">&quot;)</code>. For example, the expression <code class="cCode">${book.title}</code> returns the value of the title entry of a book map.
</p>
<a name="wp70191"> </a><p class="pBody">
The Duke's Bookstore page <code class="cCode"><a  href="../examples/web/bookstore4/web/bookdetails.txt" target="_blank">bookdetails.jsp</a></code> retrieves the column values from the <code class="cCode">book</code> map as follows.
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
&lt;c:forEach var=&quot;book&quot; begin=&quot;0&quot; items=&quot;${books.rows}&quot;&gt;
&nbsp;&nbsp;&lt;h2&gt;${book.title}&lt;/h2&gt;
&nbsp;&nbsp;&amp;nbsp;&lt;fmt:message key=&quot;By&quot;/&gt; &lt;em&gt;${book.firstname}
&nbsp;&nbsp;${book.surname}&lt;/em&gt;&amp;nbsp;&amp;nbsp;
&nbsp;&nbsp;(${book.year})&lt;br&gt; &amp;nbsp; &lt;br&gt;
&nbsp;&nbsp;&lt;h4&gt;&lt;fmt:message key=&quot;Critics&quot;/&gt;&lt;/h4&gt;
&nbsp;&nbsp;&lt;blockquote&gt;${book.description}&lt;/blockquote&gt;
&nbsp;&nbsp;&lt;h4&gt;&lt;fmt:message key=&quot;ItemPrice&quot;/&gt;: 
&nbsp;&nbsp;&lt;fmt:formatNumber value=&quot;${book.price}&quot; type=&quot;currency&quot;/&gt; 
&nbsp;&nbsp;&lt;/h4&gt;
&lt;/c:forEach&gt;<a name="wp84884"> </a>
</pre></div>
<a name="wp68160"> </a><p class="pBody">
The following excerpt from <code class="cCode"><a  href="../examples/web/bookstore4/web/bookcatalog.txt" target="_blank">bookcatalog.jsp</a></code> uses the <code class="cCode">Row</code> interface to retrieve values from the columns of a book row using scripting language expressions. First the book row that matches a request parameter (<code class="cCode">bid</code>) is retrieved from the database. Since the <code class="cCode">bid</code> and <code class="cCode">bookRow</code> objects are later used by tags that use scripting language expressions to set attribute values and a scriptlet that adds a book to the shopping cart, both objects are declared as scripting variables using the <code class="cCode">jsp:useBean</code> tag. The page creates a bean that describes the book and scripting language expressions are used to set the book properties from book row column values. Finally the book is added to the shopping cart.
</p>
<a name="wp69951"> </a><p class="pBody">
You might want to compare this version of <code class="cCode">bookcatalog.jsp</code> to the versions in <a  href="JSPIntro.html#wp69778">JavaServer Pages Technology</a> and <a  href="JSPTags.html#wp74644">Custom Tags in JSP Pages</a> that use a book database JavaBeans component. 
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
&lt;sql:query var=&quot;books&quot; 
&nbsp;&nbsp;dataSource=&quot;${applicationScope.bookDS}&quot;&gt;
&nbsp;&nbsp;select * from PUBLIC.books where id = ?
&nbsp;&nbsp;&lt;sql:param value=&quot;${bid}&quot; /&gt;
&lt;/sql:query&gt;
&lt;c:forEach var=&quot;bookRow&quot; begin=&quot;0&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;items=&quot;${books.rowsByIndex}&quot;&gt; 
&nbsp;&nbsp;&lt;jsp:useBean id=&quot;bid&quot;  type=&quot;java.lang.String&quot; /&gt;
&nbsp;&nbsp;&lt;jsp:useBean id=&quot;bookRow&quot; type=&quot;java.lang.Object[]&quot; /&gt;
&nbsp;&nbsp;&lt;jsp:useBean id=&quot;addedBook&quot; class=&quot;database.BookDetails&quot;
&nbsp;&nbsp;&nbsp;&nbsp;scope=&quot;page&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;bookId&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[0]}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;surname&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[1]}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;firstName&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[2]}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;title&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[3]}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;price&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[4])}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;year&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[6]}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;property=&quot;description&quot; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[7]}&quot; /&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;jsp:setProperty name=&quot;addedBook&quot; property=&quot;inventory&quot;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value=&quot;${bookRow[8]}&quot; /&gt;
&nbsp;&nbsp;&lt;/jsp:useBean&gt;
&nbsp;&nbsp;&lt;% cart.add(bid, addedBook); %&gt;
&nbsp;&nbsp;...
&lt;/c:forEach&gt;<a name="wp84759"> </a>
</pre></div>
    </blockquote>

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