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<!--$Id: get.so,v 10.18 2003/10/18 19:15:52 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <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,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <a name="2"><!--meow--></a> <table width="100%"><tr valign=top> <td><b><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></b></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> </td></tr></table> <p align=center><b>Retrieving records</b></p> <p>The <a href="../../api_c/db_get.html">DB->get</a> method retrieves 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> <p>There are a few flags that you can set to customize retrieval:</p> <br> <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 if both the key and the data items match those stored in the database.</ul> <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 retrieval. This can enhance performance in threaded applications by reducing the chance of deadlock.</ul> <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 is possible to search it by logical record number, retrieve a specific record.</ul> <br> <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.</p> <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> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> </body> </html>
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