mysql operation class written in php_PHP tutorial

class Db{

 private $con;
 
 
 function __construct($mysql_data){
 
  $this->db_connect($mysql_data);
 
 }
 /**
* Connect to database
* @param array $mysql_data Database connection information array('host'=>'Host: port','user'=>'User','pass'=>'Password','dbbase'=>' Database','charset'=>'Character type')
**/
 function db_connect($mysql_data){
 
  $host = $mysql_data['host'];
  $user   = $mysql_data['user'];
  $pass   = $mysql_data['pass'];
  $dbbase = $mysql_data['dbbase'];
  $charset= $mysql_data['charset'];
 
  $this->con  = @mysql_connect($host,$user,$pass) or die('NO SERVER');
  if($this->con){
   mysql_select_db($dbbase,$this->con) or die('NO DATABASE:'.$dbbase);
  
    mysql_query('set names '.$charset);
  }
 }
 
 
 /**
* Execute sql statement
* @param string $sql The sql to be executed
* @return obj
**/
 function query($sql){
 
  return mysql_query($sql,$this->con);
 
 }

 
 /**
* Get a query result
* @param string $sql The sql to be executed
* @return array array('id'=>'1','dd'=>'2');
**/
 function fetch_row($sql){
 
  $result = $this->query($sql);
 
  return mysql_fetch_assoc($result);
 }
 
 /**
* Get the first field value of a result
* @param string $sql The sql to be executed
* @return string
**/
 function fetch_first($sql){
 
  $result = $this->query($sql);
 
  $result =  mysql_fetch_array($result);
 
  return $result[0];
 }
 
 
 /**
* Return the result set
* @param string $sql The sql to be executed
* @param string $filed The field that needs to be used as an index
* @return array array(array('id'=>'1','dd'=>'2'),array('id'=>'1','dd'=>'2' ));
**/
 function fetch_result($sql,$field = null){
 
  $result  = $this->query($sql);
  $ret_array  = array();
 
  while($rows = mysql_fetch_assoc($result)){
  
   if($field){
    $ret_array[$rows[$field]]= $rows;
   }else{
    $ret_array[]= $rows;
   }
  
  }
 
  return  $ret_array;
 }
 
 /**
* Get the new ID
* @return int
**/
 function get_insertid(){
  return mysql_insert_id();
 }
 
 /**
* Single data table insertion
* @param array $Data array('Field 1'=>'Value','Field 2'=>'Value',)
* @param string $table table name
**/
 function insert($Data,$table){
 
  //insert into table (字段，字段) values(值，值)
 
  $key_array = implode(',',array_keys($Data));
  $key_val   = '''.implode('','',array_values($Data)).''';
 
  $sql       = "insert into ".$table." ($key_array) values($key_val)";
 
  return $this->query($sql);
 }
 
 
 
 /**
* Update single table
* @param array $Data array('Field 1'=>'Value','Field 2'=>'Value',)
* @param array $where array('Field 1'=>'Value','Field 2'=>'Value',)Conditions that need to be updated
* @param string $table table name www.2cto.com
**/
 function update($Data,$table,$where){
  //update table set 字段=值，字段=值 where key =value;
  $key_var = array();
 
  foreach($Data as $key=>$val){
  
   $key_var[] = $key."='".$val."'";
  }
 
  $key_var = implode(',',$key_var);
 
 
  $whe_var = array();
 
  foreach($where as $key=>$val){
  
   $whe_var[] = $key."='".$val."'";
  }
 
  $whe_var = implode(' and ',$whe_var);
 
  if($whe_var){
   $whe_var = ' where '.$whe_var;
  }
 
  $sql = "update ".$table." set ".$key_var.$whe_var;
  return $this->query($sql);
  //return $sql;
  
 }
}