PHP 모델 모델 클래스 패키지 데이터베이스 작업 예제

<?php
  //      
  include "./config.php";
  class Model
  {
    public $link;//      
    public $tableName = "";//    
    public $field = "*";//    
    public $allFields = [];//         
    public $where = "";//  where  
    public $order = "";//  order  
    public $limit = "";//  limit  
    /**
     *         
     * @param string $tableName       
     */
    public function __construct($tableName)
    {
      //1.       
      $this->tableName = PRE.$tableName;
      //2.        
      $this->getConnect();
      //3.          
      $this->getFields();
    }
    /**
     *           
     */
    public function getConnect()
    {
      //1.     
      $this->link = mysqli_connect(HOST,USER,PWD,DB,PORT);
      //2.    
      if (mysqli_connect_errno($this->link)>0){
        echo mysqli_connect_error($this->link);
        exit;
      }
    }
    /**
     *      SQL(  )
     * @param string $sql     SQL  
     * @return array            
     */
    public function query($sql)
    {
      $result = mysqli_query($this->link,$sql);
      if ($result && mysqli_num_rows($result)>0) {
       $arr = [];
       while($row = mysqli_fetch_assoc($result)){
          $arr[] = $row;
       }
      }
    return $arr;
    }
    /**
     *           
     */
    public function getFields()
    {
      //     
      $sql = "desc {$this->tableName}";
      //     SQL
      $result = $this->query($sql);
      $fields = [];
      foreach ($result as $k => $v){
        $fields[] = $v['Field'];
      }
      $this->allFields = $fields;
    }
    /**
     *      SQL  (   )
     * @param string $sql     SQL  
     * @return bool|int|string             id,         true,     false
     */
    public function exec($sql)
    {
      $result = mysqli_query($this->link,$sql);
      //     
      if ($result && mysqli_affected_rows($this->link)>0){
        //         ，          id
        if (mysqli_insert_id($this->link)){
          return mysqli_insert_id($this->link);
        }
        //           true
        return true;
      }else{
        //        false
        return false;
      }
    }
    /**
     *       
     */
    public function select()
    {
      $sql = "select {$this->field} from {$this->tableName} {$this->where} {$this->order} {$this->limit}";
      //     SQL
      return $this->query($sql);
    }
    /**
     *       
     * @param string $id     id
     * @return array       
     */
    public function find($id="")
    {
      //  id    
      if (empty($id)){
        $where = $this->where;
      }else{
        $where = "where id={$id}";
      }
      $sql = "select {$this->field} from {$this->tableName} {$where} limit 1";
      //     sql
      $result = $this->query($sql);
      //      
      return $result[0];
    }
    /**
     *           
     * @param string $field       
     * @return object     ，      
     */
    public function field($field)
    {
      //        
      if (empty($field)){
        return $this;
      }
      $this->field = $field;
      return $this;
    }
    /**
     *      
     * @return int     
     */
    public function count()
    {
      //  SQL  
      $sql = "select count(*) as total from {$this->tableName} limit 1";
      $result = $this->query($sql);
      //    
      return $result[0]['total'];
    }
    /**
     *     
     * @param array $data       
     * @return bool|int|string              id,     false
     */
    public function add($data){
      //       
      if (!is_array($data)){
        return $this;
      }
      //          
      if (empty($data)){
        die("    ");
      }
      //      
      foreach ($data as $k => $v){
        if (!in_array($k,$this->allFields)){
          unset($data[$k]);
        }
      }
      //        
      $keys = array_keys($data);
      //               
      $key = implode(",",$keys);
      //              
      $value = implode("','",$data);
      //  SQL  
      $sql = "insert into {$this->tableName} ({$key}) values('{$value}')";
      //     SQL
      return $this->exec($sql);
    }
    /**
     *     
     * @param string $id     id
     * @return bool        true,     false
     */
    public function delete($id="")
    {
      //  id    
      if (empty($id)){
        $where = $this->where;
      }else{
        $where = "where id={$id}";
      }
      $sql = "delete from {$this->tableName} {$where}";
      echo $sql;
      //     
      return $this->exec($sql);
    }
    /**
     *     
     * @param array $data       
     * @return bool       true，    false
     */
    public function update($data){
      //       
      if (!is_array($data)){
        return $this;
      }
      //           
      if(empty($data)){
        die("    ");
      }
      $str = "";
      //      
      foreach ($data as $k => $v){
        if ($k == "id"){
          $where = "where id={$v}";
          unset($data[$k]);
        }
        if (in_array($k,$this->allFields)){
          $str .= "{$k}='{$v}',";
        }else{
          unset($data[$k]);
        }
      }
      //       
      if (empty($this->where)){
        die("     ");
      }
      //        
      $str = rtrim($str,",");
      $sql = "update {$this->tableName} set {$str} {$this->where}";
      return $this->exec($sql);
    }
    /**
     * where  
     * @param string $where    where  
     * @return $this     ，      
     */
    public function where($where)
    {
      $this->where = "where ".$where;
      return $this;
    }
    /**
     * order    
     * @param string $order          
     * @return $this     ，      
     */
    public function order($order)
    {
      $this->order = "order by ".$order;
      return $this;
    }
    /**
     * limit  
     * @param string $limit    limit  
     * @return $this     ，      
     */
    public function limit($limit)
    {
      $this->limit = "limit ".$limit;
      return $this;
    }
    /**
     *     
     *        
     */
    public function __destruct()
    {
      mysqli_close($this->link);
    }
  }
 //    
 $a = new Model("  ");
 // var_dump($a->find(3));
 // var_dump($a->select());
  // var_dump($a->count());
  // $res = $a->select();
  //var_dump($res);
?>