Import BSDDB 4.7.25 (as of svn r89086)
This commit is contained in:
Zachary Ware
181
docs/gsg/JAVA/DB.html
Normal file
181
docs/gsg/JAVA/DB.html
Normal file
@@ -0,0 +1,181 @@
|
||||
<?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 7. Databases</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="baseapi.html" title="Part II. Programming with the Base API" />
|
||||
<link rel="next" href="coredbclose.html" title="Closing Databases" />
|
||||
</head>
|
||||
<body>
|
||||
<div class="navheader">
|
||||
<table width="100%" summary="Navigation header">
|
||||
<tr>
|
||||
<th colspan="3" align="center">Chapter 7. Databases</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="20%" align="left"><a accesskey="p" href="baseapi.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="coredbclose.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="DB"></a>Chapter 7. Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
<div></div>
|
||||
</div>
|
||||
<div class="toc">
|
||||
<p>
|
||||
<b>Table of Contents</b>
|
||||
</p>
|
||||
<dl>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DB.html#DBOpen">Opening Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="coredbclose.html">Closing Databases</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DBConfig.html">Database Properties</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="DBAdmin.html">Administrative Methods</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="dbErrorReporting.html">Error Reporting Functions</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="CoreEnvUsage.html">Managing Databases in Environments</a>
|
||||
</span>
|
||||
</dt>
|
||||
<dt>
|
||||
<span class="sect1">
|
||||
<a href="CoreJavaUsage.html">Database Example</a>
|
||||
</span>
|
||||
</dt>
|
||||
</dl>
|
||||
</div>
|
||||
<p>In Berkeley DB, a database is a collection of <span class="emphasis"><em>records</em></span>. Records,
|
||||
in turn, consist of key/data pairings.
|
||||
</p>
|
||||
<p>
|
||||
Conceptually, you can think of a
|
||||
<tt class="classname">Database</tt>
|
||||
|
||||
as containing a two-column table where column 1 contains a key and column 2
|
||||
contains data. Both the key and the data are managed using
|
||||
<tt class="classname">DatabaseEntry</tt>
|
||||
|
||||
|
||||
<span>class instances</span>
|
||||
|
||||
(see <a href="DBEntry.html">Database Records</a> for details on this
|
||||
<span>class</span>
|
||||
).
|
||||
So, fundamentally, using a DB
|
||||
<tt class="classname">Database</tt>
|
||||
|
||||
involves putting, getting, and deleting database records, which in turns involves efficiently
|
||||
managing information
|
||||
<span>encapsulated by </span>
|
||||
|
||||
|
||||
<tt class="classname">DatabaseEntry</tt>
|
||||
|
||||
|
||||
|
||||
<span>objects.</span>
|
||||
|
||||
The next several chapters of this book are dedicated to those activities.
|
||||
</p>
|
||||
<div class="sect1" lang="en" xml:lang="en">
|
||||
<div class="titlepage">
|
||||
<div>
|
||||
<div>
|
||||
<h2 class="title" style="clear: both"><a id="DBOpen"></a>Opening Databases</h2>
|
||||
</div>
|
||||
</div>
|
||||
<div></div>
|
||||
</div>
|
||||
<p>
|
||||
You open a database by instantiating a <tt class="classname">Database</tt>
|
||||
object.
|
||||
</p>
|
||||
<p>
|
||||
Note that by default, DB does not create databases if they do not already exist.
|
||||
To override this behavior, set the <a href="DBConfig.html" title="Database Properties">creation property</a> to true.
|
||||
</p>
|
||||
<p>
|
||||
The following code fragment illustrates a database open:
|
||||
|
||||
</p>
|
||||
<a id="java_db1"></a>
|
||||
<pre class="programlisting">package db.GettingStarted;
|
||||
|
||||
import com.sleepycat.db.DatabaseException;
|
||||
import com.sleepycat.db.Database;
|
||||
import com.sleepycat.db.DatabaseConfig;
|
||||
|
||||
import java.io.FileNotFoundException;
|
||||
...
|
||||
|
||||
Database myDatabase = null;
|
||||
|
||||
...
|
||||
|
||||
try {
|
||||
// Open the database. Create it if it does not already exist.
|
||||
DatabaseConfig dbConfig = new DatabaseConfig();
|
||||
dbConfig.setAllowCreate(true);
|
||||
myDatabase = new Database ("sampleDatabase.db",
|
||||
null,
|
||||
dbConfig);
|
||||
} catch (DatabaseException dbe) {
|
||||
// Exception handling goes here
|
||||
} catch (FileNotFoundException fnfe) {
|
||||
// Exception handling goes here
|
||||
}</pre>
|
||||
</div>
|
||||
</div>
|
||||
<div class="navfooter">
|
||||
<hr />
|
||||
<table width="100%" summary="Navigation footer">
|
||||
<tr>
|
||||
<td width="40%" align="left"><a accesskey="p" href="baseapi.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="coredbclose.html">Next</a></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td width="40%" align="left" valign="top">Part II. Programming with the Base API </td>
|
||||
<td width="20%" align="center">
|
||||
<a accesskey="h" href="index.html">Home</a>
|
||||
</td>
|
||||
<td width="40%" align="right" valign="top"> Closing Databases</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Reference in New Issue
Block a user