Edit File: Cursors.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>Chapter 9. Using Cursors</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="baseapi.html" title="Part II. Programming with the Base API" /> <link rel="previous" href="dbtJavaUsage.html" title="Database Usage Example" /> <link rel="next" href="Positioning.html" title="Getting Records Using the Cursor" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Chapter 9. Using Cursors</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="dbtJavaUsage.html">Prev</a> </td> <th width="60%" align="center">Part II. Programming with the Base API</th> <td width="20%" align="right"> <a accesskey="n" href="Positioning.html">Next</a></td> </tr> </table> <hr /> </div> <div class="chapter" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title"><a id="Cursors"></a>Chapter 9. Using Cursors</h2> </div> </div> <div></div> </div> <div class="toc"> <p> <b>Table of Contents</b> </p> <dl> <dt> <span class="sect1"> <a href="Cursors.html#openCursor">Opening and Closing Cursors</a> </span> </dt> <dt> <span class="sect1"> <a href="Positioning.html">Getting Records Using the Cursor</a> </span> </dt> <dd> <dl> <dt> <span class="sect2"> <a href="Positioning.html#cursorsearch">Searching for Records</a> </span> </dt> <dt> <span class="sect2"> <a href="Positioning.html#getdups">Working with Duplicate Records</a> </span> </dt> </dl> </dd> <dt> <span class="sect1"> <a href="PutEntryWCursor.html">Putting Records Using Cursors</a> </span> </dt> <dt> <span class="sect1"> <a href="DeleteEntryWCursor.html">Deleting Records Using Cursors</a> </span> </dt> <dt> <span class="sect1"> <a href="ReplacingEntryWCursor.html">Replacing Records Using Cursors</a> </span> </dt> <dt> <span class="sect1"> <a href="cursorJavaUsage.html">Cursor Example</a> </span> </dt> </dl> </div> <p> Cursors provide a mechanism by which you can iterate over the records in a database. Using cursors, you can get, put, and delete database records. If a database allows duplicate records, then cursors are <span>the easiest way that you can access anything other than the first record for a given key.</span> </p> <p> This chapter introduces cursors. It explains how to open and close them, how to use them to modify databases, and how to use them with duplicate records. </p> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="openCursor"></a>Opening and Closing Cursors</h2> </div> </div> <div></div> </div> <p> To use a cursor, you must open it using the <tt class="methodname">Database.openCursor()</tt> method. When you open a cursor, you can optionally pass it a <tt class="classname">CursorConfig</tt> object to set cursor properties. <span> The cursor properties that you can set allows you to control the isolation level that the cursor will obey. See the <i class="citetitle">Berkeley DB Getting Started with Transaction Processing</i> guide for more information. </span> </p> <p>For example:</p> <a id="java_cursor1"></a> <pre class="programlisting">package db.GettingStarted; import com.sleepycat.db.Cursor; import com.sleepycat.db.Database; import com.sleepycat.db.DatabaseException; import java.io.FileNotFoundException; ... Database myDatabase = null; Cursor myCursor = null; try { myDatabase = new Database("myDB", null, null); myCursor = myDatabase.openCursor(null, null); } catch (FileNotFoundException fnfe) { // Exception handling goes here ... } catch (DatabaseException dbe) { // Exception handling goes here ... }</pre> <p> To close the cursor, call the <tt class="methodname">Cursor.close()</tt> method. Note that if you close a database that has cursors open in it, then it will throw an exception and close any open cursors for you. For best results, close your cursors from within a <tt class="literal">finally</tt> block. </p> <a id="java_cursor2"></a> <pre class="programlisting">package db.GettingStarted; import com.sleepycat.db.Cursor; import com.sleepycat.db.Database; ... try { ... } catch ... { } finally { try { if (myCursor != null) { myCursor.close(); } if (myDatabase != null) { myDatabase.close(); } } catch(DatabaseException dbe) { System.err.println("Error in close: " + dbe.toString()); } } </pre> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="dbtJavaUsage.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="baseapi.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="Positioning.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Database Usage Example </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Getting Records Using the Cursor</td> </tr> </table> </div> </body> </html>
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