1<!--$Id: get.so,v 10.18 2003/10/18 19:15:52 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB Reference Guide: Retrieving records</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<a name="2"><!--meow--></a> 12<table width="100%"><tr valign=top> 13<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></b></td> 14<td align=right><a href="/am/opensub.html"><img src="/images/prev.gif" alt="Prev"></a><a href="/toc.html"><img src="/images/ref.gif" alt="Ref"></a><a href="/am/put.html"><img src="/images/next.gif" alt="Next"></a> 15</td></tr></table> 16<p align=center><b>Retrieving records</b></p> 17<p>The <a href="/api_c/db_get.html">DB->get</a> method retrieves records from the database. In general, 18<a href="/api_c/db_get.html">DB->get</a> takes a key and returns the associated data from the 19database.</p> 20<p>There are a few flags that you can set to customize retrieval:</p> 21<br> 22<b><a href="/api_c/db_get.html#DB_GET_BOTH">DB_GET_BOTH</a></b><ul compact><li>Search for a matching key and data item, that is, only return success 23if both the key and the data items match those stored in the database.</ul> 24<b><a href="/api_c/dbc_get.html#DB_RMW">DB_RMW</a></b><ul compact><li>Read-modify-write: acquire write locks instead of read locks during 25retrieval. This can enhance performance in threaded applications by 26reducing the chance of deadlock.</ul> 27<b><a href="/api_c/db_get.html#DB_SET_RECNO">DB_SET_RECNO</a></b><ul compact><li>If the underlying database is a Btree, and was configured so that it 28is possible to search it by logical record number, retrieve a specific 29record.</ul> 30<br> 31<p>If the database has been configured to support duplicate records, 32<a href="/api_c/db_get.html">DB->get</a> will always return the first data item in the duplicate 33set.</p> 34<table width="100%"><tr><td><br></td><td align=right><a href="/am/opensub.html"><img src="/images/prev.gif" alt="Prev"></a><a href="/toc.html"><img src="/images/ref.gif" alt="Ref"></a><a href="/am/put.html"><img src="/images/next.gif" alt="Next"></a> 35</td></tr></table> 36<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 37</body> 38</html> 39