<?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>Using Secondary Cursors</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="secondaryDelete.html" title="Deleting Secondary Database Records" /> <link rel="next" href="joins.html" title="Database Joins" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 12.1.6.1</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center"> <span xmlns="http://www.w3.org/1999/xhtml">Using Secondary Cursors</span> </th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="secondaryDelete.html">Prev</a> </td> <th width="60%" align="center">Chapter 10. Secondary Databases</th> <td width="20%" align="right"> <a accesskey="n" href="joins.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="secondaryCursor"></a> <span>Using Secondary Cursors</span> </h2> </div> </div> </div> <p> Just like cursors on a primary database, you can use <span>secondary cursors</span> to iterate over the records in a secondary database. Like <span>normal cursors,</span> you can also use <span>secondary cursors</span> to search for specific records in a database, to seek to the first or last record in the database, to get the next duplicate record, and so forth. For a complete description on cursors and their capabilities, see <a class="xref" href="Cursors.html" title="Chapter 9. Using Cursors">Using Cursors</a>. </p> <p> However, when you use <span>secondary cursors:</span> </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> Any data returned is the data contained on the primary database record referenced by the secondary record. </p> </li> <li> <p> <code class="methodname">SecondaryCursor.getSearchBoth()</code> and related methods do not search based on a key/data pair. Instead, you search based on a secondary key and a primary key. The data returned is the primary data that most closely matches the two keys provided for the search. </p> </li> </ul> </div> <p> For example, suppose you are using the databases, classes, and key <span>creators</span> described in <a class="xref" href="keyCreator.html" title="Implementing Key Creators">Implementing Key <span>Creators</span> </a>. Then the following searches for a person's name in the secondary database, and deletes all secondary and primary records that use that name. </p> <a id="java_index8"></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; import com.sleepycat.db.SecondaryCursor; ... try { SecondaryDatabase mySecondaryDatabase = null; // Database opens omitted for brevity ... String secondaryName = "John Doe"; DatabaseEntry secondaryKey = new DatabaseEntry(secondaryName.getBytes("UTF-8")); DatabaseEntry foundData = new DatabaseEntry(); SecondaryCursor mySecCursor = mySecondaryDatabase.openSecondaryCursor(null, null); OperationStatus retVal = mySecCursor.getSearchKey(secondaryKey, foundData, LockMode.DEFAULT); while (retVal == OperationStatus.SUCCESS) { mySecCursor.delete(); retVal = mySecCursor.getNextDup(secondaryKey, foundData, LockMode.DEFAULT); } } catch (Exception e) { // Exception handling goes here }</pre> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="secondaryDelete.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="joins.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Deleting Secondary Database Records </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Database Joins</td> </tr> </table> </div> </body> </html>