<?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>Replacing Records Using 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="Cursors.html" title="Chapter 9. Using Cursors" /> <link rel="prev" href="DeleteEntryWCursor.html" title="Deleting Records Using Cursors" /> <link rel="next" href="cursorJavaUsage.html" title="Cursor Example" /> </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">Replacing Records Using Cursors</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="DeleteEntryWCursor.html">Prev</a> </td> <th width="60%" align="center">Chapter 9. Using Cursors</th> <td width="20%" align="right"> <a accesskey="n" href="cursorJavaUsage.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="ReplacingEntryWCursor"></a>Replacing Records Using Cursors</h2> </div> </div> </div> <p> You replace the data for a database record by using <span> <code class="methodname">Cursor.putCurrent()</code>. </span> </p> <a id="java_cursor9"></a> <pre class="programlisting">import com.sleepycat.db.Cursor; import com.sleepycat.db.Database; import com.sleepycat.db.DatabaseEntry; import com.sleepycat.db.LockMode; import com.sleepycat.db.OperationStatus; ... Cursor cursor = null; Database myDatabase = null; try { ... // Database open omitted for brevity ... // Create DatabaseEntry objects // searchKey is some String. DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8")); DatabaseEntry theData = new DatabaseEntry(); // Open a cursor using a database handle cursor = myDatabase.openCursor(null, null); // Position the cursor. Ignoring the return value for clarity OperationStatus retVal = cursor.getSearchKey(theKey, theData, LockMode.DEFAULT); // Replacement data String replaceStr = "My replacement string"; DatabaseEntry replacementData = new DatabaseEntry(replaceStr.getBytes("UTF-8")); cursor.putCurrent(replacementData); } catch (Exception e) { // Exception handling goes here } finally { // Make sure to close the cursor cursor.close(); }</pre> <p> Note that you cannot change a record's key using this method; the key parameter is always ignored when you replace a record. </p> <p> When replacing the data portion of a record, if you are replacing a record that is a member of a sorted duplicates set, then the replacement will be successful only if the new record sorts identically to the old record. This means that if you are replacing a record that is a member of a sorted duplicates set, and if you are using the default lexicographic sort, then the replacement will fail due to violating the sort order. However, if you provide a custom sort routine that, for example, sorts based on just a few bytes out of the data item, then potentially you can perform a direct replacement and still not violate the restrictions described here. </p> <p> <span>Under these circumstances, if</span> you want to replace the data contained by a duplicate record, <span> and you are not using a custom sort routine, then </span> delete the record and create a new record with the desired key and data. </p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="DeleteEntryWCursor.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="Cursors.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="cursorJavaUsage.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Deleting Records Using Cursors </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Cursor Example</td> </tr> </table> </div> </body> </html>