Edit File: DBAdmin.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>Administrative Methods</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="DB.html" title="Chapter 7. Databases" /> <link rel="previous" href="DBConfig.html" title="Database Properties" /> <link rel="next" href="dbErrorReporting.html" title="Error Reporting Functions" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Administrative Methods</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="DBConfig.html">Prev</a> </td> <th width="60%" align="center">Chapter 7. Databases</th> <td width="20%" align="right"> <a accesskey="n" href="dbErrorReporting.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="DBAdmin"></a>Administrative Methods</h2> </div> </div> <div></div> </div> <p> Both the <tt class="classname">Environment</tt> and <tt class="classname">Database</tt> classes provide methods that are useful for manipulating databases. These methods are: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <tt class="methodname">Database.getDatabaseName()</tt> </p> <p>Returns the database's name.</p> <a id="je_db3.1"></a> <pre class="programlisting">String dbName = myDatabase.getDatabaseName();</pre> </li> <li> <p> <tt class="methodname">Database.rename()</tt> </p> <p> Renames the specified database. If no value is given for the <i class="parameter"><tt>database</tt></i> parameter, then the entire file referenced by this method is renamed. </p> <p> Never rename a database that has handles opened for it. Never rename a file that contains databases with opened handles. </p> <a id="java_db9"></a> <pre class="programlisting">import java.io.FileNotFoundException; ... myDatabase.close(); try { myDatabase.rename("mydb.db", // Database file to rename null, // Database to rename. Not used so // the entire file is renamed. "newdb.db", // New name to use. null); // DatabaseConfig object. // None provided. } catch (FileNotFoundException fnfe) { // Exception handling goes here }</pre> </li> <li> <p> <tt class="methodname">Environment.truncateDatabase()</tt> </p> <p> Deletes every record in the database and optionally returns the number of records that were deleted. Note that it is much less expensive to truncate a database without counting the number of records deleted than it is to truncate and count. </p> <a id="je_db5"></a> <pre class="programlisting">int numDiscarded = myEnv.truncate(null, // txn handle myDatabase.getDatabaseName(), // database name true); // If true, then the // number of records // deleted are counted. System.out.println("Discarded " + numDiscarded + " records from database " + myDatabase.getDatabaseName()); </pre> </li> </ul> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="DBConfig.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="DB.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="dbErrorReporting.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Database Properties </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Error Reporting Functions</td> </tr> </table> </div> </body> </html>
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