php 数据库访问类

class DB_MySQL
{
//==========================
var $Host = "127.0.0.1";        //服务器地址
var $Database = "teaching_sys";        //数据库名称
var $User = "root";                //用户名
var $Password = "czhnet";        //用户密码
//==========================
var $Link_ID = 0;                //数据库连接    
var $Query_ID = 0;                //查询结果    
var $Row_Result = array();        //结果集组成的数组    
var $Field_Result = array();    //结果集字段名组成的数组
var $Affected_Rows;                //影响的行数
var $Rows;                        //结果集中记录行数
var $Fields;                    //结果集中字段个数
var $Row_Position = 0;            //记录指针位置索引

//*******************************************************
    /*** 构造函数 */
    function __construct()
    {
        $this->connect();
    }//__construct()

    /*** 析构函数 */
    function __destruct()
    {
        mysql_free_result($this->Query_ID);
        mysql_close($this->Link_ID);
    }//__destruct()

    /*** 连接服务器,选择数据库 */
    function connect($Database = "",$Host = "",$User = "",$Password = "")
    {
        if ("" == $Database)
        {
         $Database = $this->Database;
        }
        if ("" == $Host)
        {
         $Host = $this->Host;
        }
        if ("" == $User)
        {
         $User = $this->User;
        }
        if ("" == $Password)
        {
         $Password = $this->Password;
        }
        //==========================
        if ( 0 == $this->Link_ID )
        {
            $this->Link_ID=@mysql_pconnect($Host, $User, $Password);
            if (!$this->Link_ID)
            {
            $this->halt("连接数据库服务端失败!");
            }
            if (!mysql_select_db($this->Database,$this->Link_ID))
            {
            $this->halt("不能打开指定的数据库:".$this->Database);
            }
        }
        return $this->Link_ID;
    }//connect()

    /*** 释放内存 */
    function free()
    {
        if ( @mysql_free_result($this->Query_ID) )
        unset ($this->Row_Result);
        $this->Query_ID = 0;
    }//free()

    /*** 执行查询 */
    function query($Query_String)
    {
        /* 释放上次查询占用的内存 */
        if ($this->Query_ID)
        {
            $this->free();
        }
        if(0 == $this->Link_ID)
        {
            $this->connect();
        }
        //设置中文字符集
        @mysql_query("set names gb2312",$this->Link_ID);
        $this->Query_ID = @mysql_query($Query_String,$this->Link_ID);
        if (!$this->Query_ID)
        {
        $this->halt("SQL查询语句出错: ".$Query_String);
        }
        return $this->Query_ID;
    }//query()
    /*** 将结果集指针指向指定行 */
    function seek($pos)
    {
        if(@mysql_data_seek($this->Query_ID, $pos))
        {
            $this->Row_Position = $pos;
            return true;
        }
        else
        {
            $this->halt("定位结果集发生错误!");
            return false;
        }

    }//seek()

    /*** 返回结果集记录组成的数组 */
    function get_rows_array()
    {
        $this->get_rows();
        for($i=0;$i<$this->Rows;$i++)
        {
            if(!mysql_data_seek($this->Query_ID,$i))
            {
                $this->halt("mysql_data_seek查询语句出错");
            }
            $this->Row_Result[$i] = mysql_fetch_array($this->Query_ID);
        }
        return $this->Row_Result;
    }//get_rows_array()

    /*** 返回结果集字段组成的数组 */
    function get_fields_array()
    {
        $this->get_fields();
        for($i=0;$i<$this->Fields;$i++)
        {
            $obj = mysql_fetch_field($this->Query_ID,$i);
            $this->Field_Result[$i] = $obj->name;
        }
        return $this->Field_Result;
    }//get_fields_array()

    /*** 返回影响记录数 */
    function get_affected_rows()
    {
        $this->Affected_Rows = mysql_affected_rows($this->Link_ID);
        return $this->Affected_Rows;
    }//Get_Affected_Rows()

    /*** 返回结果集中记录行数 */
    function get_rows()
    {
        $this->Rows = mysql_num_rows($this->Query_ID);
        return $this->Rows;
    }//Get_Rows()

    /*** 返回结果集中字段个数 */
    function get_fields()
    {
        $this->Fields = mysql_num_fields($this->Query_ID);
        return $this->Fields;
    }//Get_Fields()

    /*** 执行SQL语句并返回由查询结果中第一行记录组成的数组 */
    function fetch_one_array($sql)
    {
        $this->query($sql);
        return mysql_fetch_array($this->Query_ID);
    }//fetch_one_array()

    /*** 打印错误信息 */
    function halt($msg)
    {
        $this->Error=mysql_error();
        printf("
数据库发生错误: %s
\n", $msg);
        printf("MySQL 返回错误信息: %s
\n",    $this->Error);
        die("脚本终止");
    }//halt()
}

?>




// 使用模板


<?php
require("./db_mysql.class.php");
$DB = new DB_MySQL;
$sql = "select * from student";
$DB->query($sql);
$result = $DB->get_rows_array();
$DB->get_fields_array();
echo $DB->get_affected_rows();
echo "
";
echo print_r($DB->Field_Result);
echo "

";



echo $result[0]['name'].'
';

foreach($result as $v)

{

    echo $v['name'].'
';

    print_r($v);

}

?>