<!--$Id: get.so,v 10.15 2000/12/18 21:05:13 bostic Exp $--> <!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <html> <head> <title>Berkeley DB Reference Guide: Retrieving records</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"> </head> <body bgcolor=white> <a name="2"><!--meow--></a> <table><tr valign=top> <td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></h3></td> <td width="1%"><a href="../../ref/am/upgrade.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/am/put.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p> <h1 align=center>Retrieving records</h1> <p>The <a href="../../api_c/db_get.html">DB->get</a> function is the standard interface for retrieving records from the database. In general, <a href="../../api_c/db_get.html">DB->get</a> takes a key and returns the associated data from the database. <p>There are a few flags that you can set to customize retrieval: <p><dl compact> <p><dt><a href="../../api_c/db_get.html#DB_GET_BOTH">DB_GET_BOTH</a><dd>Search for a matching key and data item, i.e., only return success if both the key and the data items match those stored in the database. <p><dt><a href="../../api_c/dbc_get.html#DB_RMW">DB_RMW</a><dd>Read-modify-write: acquire write locks instead of read locks during retrieval. This can enhance performance in threaded applications by reducing the chance of deadlock. <p><dt><a href="../../api_c/db_get.html#DB_SET_RECNO">DB_SET_RECNO</a><dd>If the underlying database is a Btree, and was configured so that it is possible to search it by logical record number, retrieve a specific record. </dl> <p>If the database has been configured to support duplicate records, <a href="../../api_c/db_get.html">DB->get</a> will always return the first data item in the duplicate set. <table><tr><td><br></td><td width="1%"><a href="../../ref/am/upgrade.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/am/put.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font> </body> </html>