下面一个自己开发应用中会常用到的一款数据库操作类代码，下面有两个文件一个是配置文件一个是操作数据库类，最后简单的列举了这个例类的调用方法。
配置文件 config.db.php
 代码如下 复制代码
数据库操作类
 代码如下 复制代码
time = $this->microtime_float();
        require_once(config.db.php);
        $this->connect($db_config[hostname], $db_config[username], $db_config[password], $db_config[database], $db_config[pconnect]);
        $this->is_log = $db_config[log];
        if($this->is_log){
            $handle = fopen($db_config[logfilepath].dblog.txt, a+);
            $this->handle=$handle;
        }
    }
//数据库连接
    public function connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect = 0,$charset='utf8') {
        if( $pconnect==0 ) {
            $this->link_id = @mysql_connect($dbhost, $dbuser, $dbpw, true);
            if(!$this->link_id){
                $this->halt(数据库连接失败);
            }
        } else {
            $this->link_id = @mysql_pconnect($dbhost, $dbuser, $dbpw);
            if(!$this->link_id){
                $this->halt(数据库持久连接失败);
            }
        }
        if(select_db($dbname,$this-%3elink_id>!@mysql_select_db($dbname,$this->link_id)) {
            $this->halt('数据库选择失败');
        }
        @mysql_query(set names .$charset);
    }
//查询
    public function query($sql) {
        $this->write_log(查询 .$sql);
        $query = mysql_query($sql,$this->link_id);
        if(!$query) $this->halt('query error: ' . $sql);
        return $query;
    }
//获取一条记录（mysql_assoc，mysql_num，mysql_both）           
    public function get_one($sql,$result_type = mysql_assoc) {
        $query = $this->query($sql);
        $rt =& mysql_fetch_array($query,$result_type);
        $this->write_log(获取一条记录 .$sql);
        return $rt;
    }
//获取全部记录
    public function get_all($sql,$result_type = mysql_assoc) {
        $query = $this->query($sql);
        $i = 0;
        $rt = array();
        while($row =& mysql_fetch_array($query,$result_type)) {
            $rt[$i]=$row;
            $i++;
        }
        $this->write_log(获取全部记录 .$sql);
        return $rt;
    }
//插入
    public function insert($table,$dataarray) {
        $field = ;
        $value = ;
        if( !is_array($dataarray) || count($dataarray)            $this->halt('没有要插入的数据');
            return false;
        }
        while(list($key,$val)=each($dataarray)) {
            $field .=$key,;
            $value .='$val',;
        }
        $field = substr( $field,0,-1);
        $value = substr( $value,0,-1);
        $sql = insert into $table($field) values($value);
        $this->write_log(插入 .$sql);
        if(!$this->query($sql)) return false;
        return true;
    }
//更新
    public function update( $table,$dataarray,$condition=) {
        if( !is_array($dataarray) || count($dataarray)            $this->halt('没有要更新的数据');
            return false;
        }
        $value = ;
        while( list($key,$val) = each($dataarray))
        $value .= $key = '$val',;
        $value .= substr( $value,0,-1);
        $sql = update $table set $value where 1=1 and $condition;
        $this->write_log(更新 .$sql);
        if(!$this->query($sql)) return false;
        return true;
    }
//删除
    public function delete( $table,$condition=) {
        if( empty($condition) ) {
            $this->halt('没有设置删除的条件');
            return false;
        }
        $sql = delete from $table where 1=1 and $condition;
        $this->write_log(删除 .$sql);
        if(!$this->query($sql)) return false;
        return true;
    }
//返回结果集
    public function fetch_array($query, $result_type = mysql_assoc){
        $this->write_log(返回结果集);
        return mysql_fetch_array($query, $result_type);
    }
//获取记录条数
    public function num_rows($results) {
        if(!is_bool($results)) {
            $num = mysql_num_rows($results);
            $this->write_log(获取的记录条数为.$num);
            return $num;
        } else {
            return 0;
        }
    }
//释放结果集
    public function free_result() {
        $void = func_get_args();
        foreach($void as $query) {
            if(is_resource($query) && get_resource_type($query) === 'mysql result') {
                return mysql_free_result($query);
            }
        }
        $this->write_log(释放结果集);
    }
//获取最后插入的id
    public function insert_id() {
        $id = mysql_insert_id($this->link_id);
        $this->write_log(最后插入的id为.$id);
        return $id;
    }
//关闭数据库连接
    protected function close() {
        $this->write_log(已关闭数据库连接);
        return @mysql_close($this->link_id);
    }
//错误提示
    private function halt($msg='') {
        $msg .= ＼r＼n.mysql_error();
        $this->write_log($msg);
        die($msg);
    }
//析构函数
    public function __destruct() {
        $this->free_result();
        $use_time = ($this-> microtime_float())-($this->time);
        $this->write_log(完成整个查询任务,所用时间为.$use_time);
        if($this->is_log){
            fclose($this->handle);
        }
    }
//写入日志文件
    public function write_log($msg=''){
        if($this->is_log){
            $text = date(y-m-d h:i:s). .$msg.＼r＼n;
            fwrite($this->handle,$text);
        }
    }
//获取毫秒数
    public function microtime_float() {
        list($usec, $sec) = explode( , microtime());
        return ((float)$usec + (float)$sec);
    }
}
?>
使用方法
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$db = new db();
调用
$db->insert_id();//获取最新ip地址