<!--$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><metaname="description"content="Berkeley DB: An embedded database programmatic toolkit."><metaname="keywords"content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"></head><bodybgcolor=white><aname="2"><!--meow--></a><table><trvalign=top><td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></h3></td><tdwidth="1%"><ahref="../../ref/am/upgrade.html"><imgsrc="../../images/prev.gif"alt="Prev"></a><ahref="../../ref/toc.html"><imgsrc="../../images/ref.gif"alt="Ref"></a><ahref="../../ref/am/put.html"><imgsrc="../../images/next.gif"alt="Next"></a></td></tr></table><p><h1align=center>Retrieving records</h1><p>The <ahref="../../api_c/db_get.html">DB->get</a> function is the standard interface for retrieving records fromthe database. In general, <ahref="../../api_c/db_get.html">DB->get</a> takes a key and returns theassociated data from the database.<p>There are a few flags that you can set to customize retrieval:<p><dlcompact><p><dt><ahref="../../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 boththe key and the data items match those stored in the database.<p><dt><ahref="../../api_c/dbc_get.html#DB_RMW">DB_RMW</a><dd>Read-modify-write: acquire write locks instead of read locks duringretrieval. This can enhance performance in threaded applications byreducing the chance of deadlock.<p><dt><ahref="../../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 itis possible to search it by logical record number, retrieve a specificrecord.</dl><p>If the database has been configured to support duplicate records,<ahref="../../api_c/db_get.html">DB->get</a> will always return the first data item in the duplicateset.<table><tr><td><br></td><tdwidth="1%"><ahref="../../ref/am/upgrade.html"><imgsrc="../../images/prev.gif"alt="Prev"></a><ahref="../../ref/toc.html"><imgsrc="../../images/ref.gif"alt="Ref"></a><ahref="../../ref/am/put.html"><imgsrc="../../images/next.gif"alt="Next"></a></td></tr></table><p><fontsize=1><ahref="http://www.sleepycat.com">Copyright Sleepycat Software</a></font></body></html>