diff options
| author | jbj <devnull@localhost> | 2001-03-21 18:33:35 +0000 |
|---|---|---|
| committer | jbj <devnull@localhost> | 2001-03-21 18:33:35 +0000 |
| commit | 731946f4b90eb1173452dd30f1296dd825155d82 (patch) | |
| tree | 67535f54ecb7e5463c06e62044e4efd84ae0291d /db/docs/ref/simple_tut/del.html | |
| parent | 7ed904da030dc4640ff9bce8458ba07cc09d830d (diff) | |
| download | librpm-tizen-731946f4b90eb1173452dd30f1296dd825155d82.tar.gz librpm-tizen-731946f4b90eb1173452dd30f1296dd825155d82.tar.bz2 librpm-tizen-731946f4b90eb1173452dd30f1296dd825155d82.zip | |
Initial revision
CVS patchset: 4644
CVS date: 2001/03/21 18:33:35
Diffstat (limited to 'db/docs/ref/simple_tut/del.html')
| -rw-r--r-- | db/docs/ref/simple_tut/del.html | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/db/docs/ref/simple_tut/del.html b/db/docs/ref/simple_tut/del.html new file mode 100644 index 000000000..ac4d41260 --- /dev/null +++ b/db/docs/ref/simple_tut/del.html @@ -0,0 +1,93 @@ +<!--$Id: del.so,v 10.20 2000/03/18 21:43:17 bostic Exp $--> +<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> +<!--All rights reserved.--> +<html> +<head> +<title>Berkeley DB Reference Guide: Removing elements from a database</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> +<table><tr valign=top> +<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Simple Tutorial</dl></h3></td> +<td width="1%"><a href="../../ref/simple_tut/get.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/simple_tut/close.html"><img src="../../images/next.gif" alt="Next"></a> +</td></tr></table> +<p> +<h1 align=center>Removing elements from a database</h1> +<p>The simplest way to remove elements from a database is the <a href="../../api_c/db_del.html">DB->del</a> +interface. +<p>The <a href="../../api_c/db_del.html">DB->del</a> interface takes four of the same five arguments that +the <a href="../../api_c/db_get.html">DB->get</a> and <a href="../../api_c/db_put.html">DB->put</a> interfaces take. The difference +is that there is no need to specify a data item, as the delete operation +is only interested in the key that you want to remove. +<p><dl compact> +<p><dt>db<dd>The database handle returned by <a href="../../api_c/db_create.html">db_create</a>. +<p><dt>txnid<dd>A transaction ID. +In our simple case, we aren't expecting to recover the database after +application or system crash, so we aren't using transactions, and will +leave this argument unspecified. +<p><dt>key<dd>The key item for the key/data pair that we want to delete from the +database. +<p><dt>flags<dd>Optional flags modifying the underlying behavior of the <a href="../../api_c/db_del.html">DB->del</a> +interface. There are currently no available flags for this interface, +so the flags argument should always be set to 0. +</dl> +<p>Here's what the code to call <a href="../../api_c/db_del.html">DB->del</a> looks like: +<p><blockquote><pre>#include <sys/types.h> +#include <stdio.h> +#include <db.h> +<p> +#define DATABASE "access.db" +<p> +int +main() +{ + DB *dbp; + DBT key, data; + int ret; +<p> + if ((ret = db_create(&dbp, NULL, 0)) != 0) { + fprintf(stderr, "db_create: %s\n", db_strerror(ret)); + exit (1); + } + if ((ret = dbp->open( + dbp, DATABASE, NULL, DB_BTREE, DB_CREATE, 0664)) != 0) { + dbp->err(dbp, ret, "%s", DATABASE); + goto err; + } +<p> + memset(&key, 0, sizeof(key)); + memset(&data, 0, sizeof(data)); + key.data = "fruit"; + key.size = sizeof("fruit"); + data.data = "apple"; + data.size = sizeof("apple"); +<p> + if ((ret = dbp->put(dbp, NULL, &key, &data, 0)) == 0) + printf("db: %s: key stored.\n", (char *)key.data); + else { + dbp->err(dbp, ret, "DB->put"); + goto err; + } +<p> + if ((ret = dbp->get(dbp, NULL, &key, &data, 0)) == 0) + printf("db: %s: key retrieved: data was %s.\n", + (char *)key.data, (char *)data.data); + else { + dbp->err(dbp, ret, "DB->get"); + goto err; + } +<p><b> if ((ret = dbp->del(dbp, NULL, &key, 0)) == 0) + printf("db: %s: key was deleted.\n", (char *)key.data); + else { + dbp->err(dbp, ret, "DB->del"); + goto err; + } +</b></pre></blockquote> +<p>After the <a href="../../api_c/db_del.html">DB->del</a> call returns, the entry referenced by the key +fruit has been removed from the database. +<table><tr><td><br></td><td width="1%"><a href="../../ref/simple_tut/get.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/simple_tut/close.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> |