CHips L MINI SHELL

CHips L pro

Current Path : /usr/share/doc/db4-devel-4.7.25/gsg/JAVA/
Upload File :
Current File : //usr/share/doc/db4-devel-4.7.25/gsg/JAVA/readSecondary.html

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>Reading Secondary Databases</title>
    <link rel="stylesheet" href="gettingStarted.css" type="text/css" />
    <meta name="generator" content="DocBook XSL Stylesheets V1.62.4" />
    <link rel="home" href="index.html" title="Getting Started with Berkeley DB" />
    <link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" />
    <link rel="previous" href="secondaryProps.html" title="Secondary Database Properties" />
    <link rel="next" href="secondaryDelete.html" title="Deleting Secondary Database Records" />
  </head>
  <body>
    <div class="navheader">
      <table width="100%" summary="Navigation header">
        <tr>
          <th colspan="3" align="center">Reading Secondary Databases</th>
        </tr>
        <tr>
          <td width="20%" align="left"><a accesskey="p" href="secondaryProps.html">Prev</a> </td>
          <th width="60%" align="center">Chapter 10. Secondary Databases</th>
          <td width="20%" align="right"> <a accesskey="n" href="secondaryDelete.html">Next</a></td>
        </tr>
      </table>
      <hr />
    </div>
    <div class="sect1" lang="en" xml:lang="en">
      <div class="titlepage">
        <div>
          <div>
            <h2 class="title" style="clear: both"><a id="readSecondary"></a>Reading Secondary Databases</h2>
          </div>
        </div>
        <div></div>
      </div>
      <p>
        Like a primary database, you can read records from your secondary
        database either by using the 
            <span>
                <tt class="methodname">SecondaryDatabase.get()</tt> method,
            </span>
            
        or by using  
            <span>a <tt class="classname">SecondaryCursor</tt>.</span> 
             
            
        The main difference between reading secondary and primary databases is that when
        you read a secondary database record, the secondary record's data is not
        returned to you. Instead, the primary key and data corresponding to the
        secondary key are returned to you.
    </p>
      <p>
        For example, assuming your secondary database contains keys related
         to a person's full name:
    </p>
      <a id="java_index6"></a>
      <pre class="programlisting">package db.GettingStarted;

import com.sleepycat.db.DatabaseEntry;
import com.sleepycat.db.LockMode;
import com.sleepycat.db.OperationStatus;
import com.sleepycat.db.SecondaryDatabase;

...
SecondaryDatabase mySecondaryDatabase = null;
try {
    // Omitting all database opens
    ...

    String searchName = "John Doe";
    DatabaseEntry searchKey = 
        new DatabaseEntry(searchName.getBytes("UTF-8"));
    DatabaseEntry primaryKey = new DatabaseEntry();
    DatabaseEntry primaryData = new DatabaseEntry();

    // Get the primary key and data for the user 'John Doe'.
    OperationStatus retVal = mySecondaryDatabase.get(null, searchKey, 
                                                     primaryKey, 
                                                     primaryData, 
                                                     LockMode.DEFAULT); 
} catch (Exception e) {
    // Exception handling goes here
}</pre>
      <p>
        Note that, just like 
            <span><tt class="methodname">Database.get()</tt>, </span>
            
            
        if your secondary database supports duplicate records then
            <tt class="methodname">SecondaryDatabase.get()</tt> 
            
        only return the first record found in a matching duplicates set. If you 
        want to see all the records related to a specific secondary key, then use a
            <span>
                <tt class="classname">SecondaryCursor</tt> (described in <a href="secondaryCursor.html">
        <span>Using Secondary Cursors</span>
        
    </a>).
            </span>
            
     </p>
    </div>
    <div class="navfooter">
      <hr />
      <table width="100%" summary="Navigation footer">
        <tr>
          <td width="40%" align="left"><a accesskey="p" href="secondaryProps.html">Prev</a> </td>
          <td width="20%" align="center">
            <a accesskey="u" href="indexes.html">Up</a>
          </td>
          <td width="40%" align="right"> <a accesskey="n" href="secondaryDelete.html">Next</a></td>
        </tr>
        <tr>
          <td width="40%" align="left" valign="top">Secondary Database Properties </td>
          <td width="20%" align="center">
            <a accesskey="h" href="index.html">Home</a>
          </td>
          <td width="40%" align="right" valign="top"> Deleting Secondary Database Records</td>
        </tr>
      </table>
    </div>
  </body>
</html>

Copyright 2K16 - 2K18 Indonesian Hacker Rulez