<?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 V1.73.2" /> <link rel="start" href="index.html" title="Getting Started with Berkeley DB" /> <link rel="up" href="indexes.html" title="Chapter 10. Secondary Databases" /> <link rel="prev" 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> <p> Like a primary database, you can read records from your secondary database either by using the <span> <code class="methodname">SecondaryDatabase.get()</code> method, </span> or by using <span>a <code class="classname">SecondaryCursor</code>.</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><code class="methodname">Database.get()</code>, </span> if your secondary database supports duplicate records then <code class="methodname">SecondaryDatabase.get()</code> 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> <code class="classname">SecondaryCursor</code> (described in <a class="xref" href="secondaryCursor.html" title="Using Secondary Cursors"> <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>