一个数据库操作PHP类

    /*
    *   Author  墨龙
    *   Time    2010年12月2日 15:50:35
    */

    $db = new mysql($db_host,$db_user,$db_password,$db_table,$db_conn,$pre,$coding);

    class mysql{

        private    $db_host;
        private    $db_user;
        private    $db_password;
        private    $db_table;
        private    $db_conn;           //数据库连接标识;
        private    $result;         //执行query命令的结果资源标识
        private    $sql;      //sql执行语句
        private    $pre;      //数据库表前缀
        private    $coding;  //数据库编码，GBK,UTF8,gb2312

        function __construct($db_host,$db_user,$db_password,$db_table,$db_conn,$pre,$coding){

            $this->db_host     = $db_host;
            $this->db_user     = $db_user;
            $this->db_password = $db_password;
            $this->db_table    = $db_table;
            $this->db_conn     = $db_conn;
            $this->pre         = $pre;
            $this->coding      = $coding;
            $this->connect();

        }

        function connect(){

            $this->db_conn = @mysql_connect($this->db_host,$this->db_user,$this->db_password) or die($this->show_error("数据库链接错误,请检查数据库链接配置！"));
            if(!mysql_select_db($this->db_table,$this->db_conn)){

                echo "没有找到数据表：".$this->db_table;
            }
            mysql_select_db($this->db_table,$this->db_conn);
            $this->query("SET NAMES $this->coding");
        }

        /*执行SQL语句的函数*/
        function query($sql){

            if(emptyempty($sql)){
                $this->show_error("你的sql语句不能为空！");
            }else{
                $this->sql = $sql;
            }
            $result = mysql_query($this->sql,$this->db_conn);

            return $this->result = $result;
        }

        /*创建添加新的数据库*/
        public function create_database($database_name){
            $database=$database_name;
            $sqlDatabase = 'create database '.$database;
            return $this->query($sqlDatabase);
        }

        // 根据select查询结果计算结果集条数
        public function db_num_rows(){
             if($this->result==null){
                if($this->show_error){
                    $this->show_error("sql语句错误!");
                }
             }else{
                return  mysql_num_rows($this->result);
             }
        }

        /*查询服务器所有数据库*/
        //将系统数据库与用户数据库分开，更直观的显示？
        public function show_databases(){
            $this->query("show databases");
            echo "现有数据库：".$amount =$this->db_num_rows($rs);
            echo "";
            $i=1;
            while($row = $this->fetch_array($rs)){
                echo "$i $row[Database]";
                echo "";
                $i++;
            }
        }

        //以数组形式返回主机中所有数据库名
        public function databases()
        {
            $rsPtr=mysql_list_dbs($this->db_conn);
            $i=0;
            $cnt=mysql_num_rows($rsPtr);
            while($i            {
              $rs[]=mysql_db_name($rsPtr,$i);
              $i++;
            }
            return print_r($rs);
        }

        /*查询数据库下所有的表*/
        function show_tables($database_name){
            $this->query("show tables");
            echo "现有数据库：".$amount = $this->db_num_rows($rs);
            echo "";
            $i=1;
            while($row = $this->fetch_array($rs)){
                $columnName="Tables_in_".$database_name;
                echo "$i $row[$columnName]";
                echo "";
                $i++;
            }
        }

        /*
        mysql_fetch_row()    array  $row[0],$row[1],$row[2]
        mysql_fetch_array()  array  $row[0] 或 $row[id]
        mysql_fetch_assoc()  array  用$row->content 字段大小写敏感
        mysql_fetch_object() object 用$row[id],$row[content] 字段大小写敏感
        */
        /*取得记录集,获取数组-索引和关联,使用$row['content'] */
        public function fetch_array()
        {
            return @mysql_fetch_array($this->result);
        }

        //获取关联数组,使用$row['字段名']
        public function fetch_ass()
        {
            return @mysql_fetch_assoc($this->result);
        }

        //获取数字索引数组,使用$row[0],$row[1],$row[2]
        public function fetch_row()
        {
            return @mysql_fetch_row($this->result);
        }

        //获取对象数组,使用$row->content
        public function fetch_Object()
        {
            return @mysql_fetch_object($this->result);
        }

        //简化查询select
        public function findall($table){
            $table = $this->fulltablename($table);
            $this->query("select * from $table");
        }

        public function select($table,$columnName,$condition){
            $table = $this->fulltablename($table);
            if(emptyempty($columnName)){
                $columnName = "*";
            }
            $this->query("SELECT $columnName FROM $table $condition");
        }

        //简化的insert
        function insert($table,$arr){
            $table = $this->fulltablename($table);
            $sql = "INSERT INTO $table ";
            if(!is_array($arr)){
                $this->show_error("请输入参数数组！");
            }else{
            $k = "";
            $v = "";
            foreach($arr as $key => $value){
                $k .= "`$key`,";
                $v .= "'".$value."',";
            }
            }
            $sql = $sql." (".substr($k,0,-1).") VALUES (".substr($v,0,-1).")";
            $this->query($sql);
        }
        //简化的update
        function update($table,$arr,$where){
            $table = $this->fulltablename($table);
            $sql = "UPDATE $table SET ";
            if(!is_array($arr)){
                $this->show_error("请输入参数数组！");
            }else{
            foreach($arr as $key => $value){
                $sql .= " `".$key."` = '".$value."' ,";
            }
            }
            $sql = substr($sql,0,-1)." where ".$where;
            return $this->query($sql);
        }
        //简化的delete
        function delete($table,$where = ""){
            $table = $this->fulltablename($table);
            if(emptyempty($where)){
                $this->show_error("条件不能为空!");
            }else{
                $where = " where ".$where;
            }
            $sql = "DELETE FROM $table ".$where;
            //echo $sql;
            return $this->query($sql);
        }

        //取得上一步 INSERT 操作产生的 ID
        public function insert_id(){
            return mysql_insert_id();
        }

        //加上前缀的数据表
        public function fulltablename($table){
            return $table = $this->pre.$table;
        }

        //查询字段数量
        public function num_fields($table){
            $table = $this->fulltablename($table);
            $this->query("select * from $table");
            echo "";
            echo "字段数：".$total = mysql_num_fields($this->result);
            echo "";
            for ($i=0; $i                print_r(mysql_fetch_field($this->result,$i) );
            }
            echo "";
            echo "";
        }

        //取得 MySQL 服务器信息
        public function mysql_server($num=''){
            switch ($num){
                case 1 :
                return mysql_get_server_info(); //MySQL 服务器信息
                break;

                case 2 :
                return mysql_get_host_info();   //取得 MySQL 主机信息
                break;

                case 3 :
                return mysql_get_client_info(); //取得 MySQL 客户端信息
                break;

                case 4 :
                return mysql_get_proto_info();  //取得 MySQL 协议信息
                break;

                default:
                return mysql_get_client_info(); //默认取得mysql版本信息
            }
        }

        //析构函数，自动关闭数据库,垃圾回收机制
        /*public function __destruct()
        {
            if(!empty($this->result)){
                $this->free();
            }
            mysql_close($this->$db_conn);
        }*/

        /*获得客户端真实的IP地址*/
        function getip(){
            if(getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
            {
                $ip = getenv("HTTP_CLIENT_IP");
            }
            else if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown")){
                $ip = getenv("HTTP_X_FORWARDED_FOR");
            }
            else if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
            {
                $ip = getenv("REMOTE_ADDR");
            }
            else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown")){
            $ip = $_SERVER['REMOTE_ADDR'];
            }
            else{
                $ip = "unknown";
            }
            return($ip);
        }

        function show_error($str){
            echo "";
        }

    }
    ?>

PHP