A singleton mode Mysql operation class encapsulated by PHP plays an important role in PHP. This article will explain its related knowledge in detail.

A singleton mode Mysql operation class encapsulated by PHP

Master the necessary conditions to meet the singleton mode----three private and one public.

①Private construction method-to prevent the use of the new keyword to instantiate objects outside the class.

②Private member attributes-in order to prevent the attributes of storing objects from being introduced outside the class.

③Private clone method-in order to prevent another object from being cloned outside the class.

④Public static methods-to allow users to instantiate objects.

DB class and related table operations;

class mysql_db{ 
  //1.私有的靜態(tài)屬性
  private static $dbcon = false; 
  //2.私有的構造方法
  private function __construct(){
    $dbconn = @mysql_connect("localhost","root","");
    mysql_select_db("test",$dbconn) or die("mysql_connect error");
    mysql_query("SET NAMES utf8");
  } 
  //3.私有的克隆方法
  private function __clone() {
   
  } 
  //1.公有的靜態(tài)方法
  public static function getIntance() {
    if(self::$dbcon==false){   
      self::$dbcon=new self;
    }
    return self::$dbcon;
  }
  //執(zhí)行語句
  public function query($sql) {
    $query=mysql_query($sql);   
    return $query;
  }
  /**
  * 查詢某個字段
  * @param
  * @return string or int
  */
  public function getOne($sql) {
    $query = $this->query($sql);  
    return mysql_result($query,0);
  } 
  //獲取一行記錄,return array 一維數組
  public function getRow($sql,$type="assoc") {
      $query=$this->query($sql);   
      if(!in_array($type,array("assoc",'array',"row"))) {
         die("mysql_query error");
       }
      $funcname = "mysql_fetch_".$type;  
      return $funcname($query);
  } 
  //獲取一條記錄,前置條件通過資源獲取一條記錄
  public function getFormSource($query,$type="assoc"){   
     if(!in_array($type,array("assoc","array","row"))) {
        die("mysql_query error");
     }
     $funcname = "mysql_fetch_".$type;   
     return $funcname($query);
  }  //獲取多條數據，二維數組
  public function getAll($sql){
      $query=$this->query($sql);
      $list=array();  
      while ($r=$this->getFormSource($query)) {
        $list[]=$r;
      } 
      return $list;
  } 
  //獲得最后一條記錄id
  public function getInsertid(){ 
     return mysql_insert_id();
  }   /**
   * 定義添加數據的方法
   * @param string $table 表名
   * @param string orarray $data [數據]
   * @return int 最新添加的id
   */
   public function insert($table,$data){ 
    //遍歷數組，得到每一個字段和字段的值
     $key_str='';
     $v_str='';  
     foreach($data as $key=>$v) {  
        if(empty($v)) {    
        die("error");
      }    
      //$key的值是每一個字段s一個字段所對應的值
      $key_str.=$key.',';
      $v_str.="'$v',";
   }
   $key_str=trim($key_str,',');
   $v_str=trim($v_str,',');   //判斷數據是否為空
   $sql="insert into $table ($key_str) values ($v_str)";  
   $this->query($sql);   //返回上一次增加操做產生ID值
   return mysql_insert_id();
 } /*
  * 刪除一條數據方法
  * @param1 $table, $where=array('id'=>'1') 表名 條件
  * @return 受影響的行數
  */
  public function deleteOne($table, $where){   
     if(is_array($where)){     
        foreach ($where as $key => $val) {
        $condition = $key.'='.$val;
      }
    } else {
      $condition = $where;
    }
    $sql = "delete from $table where $condition";    $this->query($sql);    //返回受影響的行數
    return mysql_affected_rows();
  }  /*
  * 刪除多條數據方法
  * @param1 $table, $where 表名 條件
  * @return 受影響的行數
  */
  public function deleteAll($table, $where){   
      if(is_array($where)){ 
          foreach ($where as $key => $val) { 
                if(is_array($val)){
          $condition = $key.' in ('.implode(',', $val) .')';
        } else {
          $condition = $key. '=' .$val;
        }
      }
    } else {
      $condition = $where;
    }
    $sql = "delete from $table where $condition";    $this->query($sql);    //返回受影響的行數
    return mysql_affected_rows();
  } /**
  * [修改操作description]
  * @param [type] $table [表名]
  * @param [type] $data [數據]
  * @param [type] $where [條件]
  * @return [type]
  */
 public function update($table,$data,$where) {   //遍歷數組，得到每一個字段和字段的值
      $str='';  foreach($data as $key=>$v){
      $str.="$key='$v',";
  }
     $str=rtrim($str,',');  //修改SQL語句
     $sql="update $table set $str where $where";  $this->query($sql);  //返回受影響的行數
     return mysql_affected_rows();
 }
}

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