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HomeBackend DevelopmentPHP TutorialPHP访问MYSQL数据库封装类

<?php
/*
MYSQL 数据库访问封装类
MYSQL 数据访问方式,php4支持以mysql_开头的过程访问方式,php5开始支持以mysqli_开头的过程和mysqli面向对象
访问方式,本封装类以mysql_封装 

 

数据访问的一般流程:
1,连接数据库 mysql_connect or mysql_pconnect
2,选择数据库 mysql_select_db
3,执行SQL查询 mysql_query
4,处理返回的数据 mysql_fetch_array mysql_num_rows mysql_fetch_assoc mysql_fetch_row etc
*/

class db_mysql
{
  var $querynum = 0 ; //当前页面进程查询数据库的次数
  var $dblink ;       //数据库连接资源
  
  //链接数据库
  function connect($dbhost,$dbuser,$dbpw,$dbname='',$dbcharset='utf-8',$pconnect=0 , $halt=true)
  {
     $func = empty($pconnect) ? 'mysql_connect' : 'mysql_pconnect' ;
     $this->dblink = @$func($dbhost,$dbuser,$dbpw) ;
     if ($halt && !$this->dblink)
     {
        $this->halt("无法链接数据库!");
     }
     
     //设置查询字符集
     mysql_query("SET character_set_connection={$dbcharset},character_set_results={$dbcharset},character_set_client=binary",$this->dblink) ;
     
     //选择数据库
     $dbname && @mysql_select_db($dbname,$this->dblink) ;
  }
  
  //选择数据库
  function select_db($dbname)
  {
     return mysql_select_db($dbname,$this->dblink);
  }
  
  //执行SQL查询
  function query($sql)
  {
     $this->querynum++ ;
     return mysql_query($sql,$this->dblink) ;
  }
  
  //返回最近一次与连接句柄关联的INSERT,UPDATE 或DELETE 查询所影响的记录行数
  function affected_rows()
  {
     return mysql_affected_rows($this->dblink) ;
  }
  
  //取得结果集中行的数目,只对select查询的结果集有效
  function num_rows($result)
  {
     return mysql_num_rows($result) ;
  }
  
  //获得单格的查询结果
  function result($result,$row=0)
  {
     return mysql_result($result,$row) ;
  }
  
  //取得上一步 INSERT 操作产生的 ID,只对表有AUTO_INCREMENT ID的操作有效
  function insert_id()
  {
     return ($id = mysql_insert_id($this->dblink)) >= 0 ? $id : $this->result($this->query("SELECT last_insert_id()"), 0);
  }
  
  //从结果集提取当前行,以数字为key表示的关联数组形式返回
  function fetch_row($result)
  {
     return mysql_fetch_row($result) ;
  }
  
  //从结果集提取当前行,以字段名为key表示的关联数组形式返回
  function fetch_assoc($result)
  {
     return mysql_fetch_assoc($result);
  }
  
  //从结果集提取当前行,以字段名和数字为key表示的关联数组形式返回
  function fetch_array($result)
  {
     return mysql_fetch_array($result);
  }
  
  //关闭链接
  function close()
  {
     return mysql_close($this->dblink) ;
  }
  
  //输出简单的错误html提示信息并终止程序
  function halt($msg)
  {
     $message = "<html>\n<head>\n" ;
     $message .= "<meta content='text/html;charset=gb2312'>\n" ;
     $message .= "</head>\n" ;
     $message .= "<body>\n" ;
     $message .= "数据库出错:".htmlspecialchars($msg)."\n" ;
     $message .= "</body>\n" ;
     $message .= "</html>" ;
     
     echo $message ;
     exit ;
  }
}
?>

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