mirror of
https://github.com/berkeleydb/je.git
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124 lines
4.5 KiB
HTML
124 lines
4.5 KiB
HTML
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Replacing Records Using Cursors</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
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<link rel="up" href="Cursors.html" title="Chapter 9. Using Cursors" />
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<link rel="prev" href="DeleteEntryWCursor.html" title="Deleting Records Using Cursors" />
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<link rel="next" href="cursorUsage.html" title="Cursor Example" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 12.2.7.5</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Replacing Records Using Cursors</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="DeleteEntryWCursor.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 9. Using Cursors</th>
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<td width="20%" align="right"> <a accesskey="n" href="cursorUsage.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="ReplacingEntryWCursor"></a>Replacing Records Using Cursors</h2>
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</div>
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</div>
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</div>
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<p>
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You replace the data for a database record by using
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<span>
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<code class="methodname">Cursor.putCurrent()</code>.
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This method takes just one
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argument — the data that you want to write to the current location in the
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database.
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</span>
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</p>
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<a id="je_cursor9"></a>
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<pre class="programlisting">import com.sleepycat.je.Cursor;
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import com.sleepycat.je.Database;
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import com.sleepycat.je.DatabaseEntry;
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import com.sleepycat.je.LockMode;
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import com.sleepycat.je.OperationStatus;
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...
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Cursor cursor = null;
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try {
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...
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// Database and environment open omitted for brevity
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...
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// Create DatabaseEntry objects
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// searchKey is some String.
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DatabaseEntry theKey = new DatabaseEntry(searchKey.getBytes("UTF-8"));
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DatabaseEntry theData = new DatabaseEntry();
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// Open a cursor using a database handle
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cursor = myDatabase.openCursor(null, null);
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// Position the cursor. Ignoring the return value for clarity
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OperationStatus retVal = cursor.getSearchKey(theKey, theData,
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LockMode.DEFAULT);
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// Replacement data
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String replaceStr = "My replacement string";
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DatabaseEntry replacementData =
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new DatabaseEntry(replaceStr.getBytes("UTF-8"));
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cursor.putCurrent(replacementData);
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} catch (Exception e) {
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// Exception handling goes here
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} finally {
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// Make sure to close the cursor
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cursor.close();
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}</pre>
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<p>
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Note that this method cannot be used if the record that you are trying
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to replace is a member of a duplicate set. This is because records must
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be sorted by their data and replacement would violate that sort order.
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</p>
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<p>
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<span>If</span>
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you want to replace the data contained by a duplicate record,
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delete the record and create a new record with the desired key and data.
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</p>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="DeleteEntryWCursor.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="Cursors.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="cursorUsage.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Deleting Records Using Cursors </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Cursor Example</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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