SQLite operation class implemented by PDO in PHP

<?php
// sqlite分页类
class SqliteDB{
  public function __construct(){
    // 初始化数据库，并且连接数据库 数据库配置
    $this->db = new PDO(&#39;sqlite:&#39;.dirname(__FILE__).&#39;\log.db&#39;);
    $this->table_name=$tab;
    $this->tab_init();
  }
  public function tab_init()
  {
    # 表初始化,创建表
    $this->db->exec("CREATE TABLE log(
      id integer PRIMARY KEY autoincrement,
      urls varchar(200),
      ip varchar(200),
      datetimes datetime default (datetime(&#39;now&#39;, &#39;localtime&#39;))
      )");
  }
  public function insert($tab_name,$key_list,$value_list)
  {
    // echo "INSERT INTO ".$tab_name." (".$key_list.") values(".$value_list.")";
    $result=$this->db->exec("INSERT INTO ".$tab_name." (".$key_list.") values(".$value_list.")");
    if (!$result) {
      return false;
    }
    // echo "{{{INSERT INTO ".$tab_name." (".$key_list.") values(".$value_list.")}}}}";
    $res=$this->db->beginTransaction();//事务回gun
  }
  public function total($tab_name,$tj=&#39;&#39;)//求总记录数目
  {
    $sth = $this->db->prepare(&#39;SELECT count(id) as c FROM &#39;.$tab_name.&#39; &#39;.$tj);
    $sth->execute();
    $result = $sth->fetchAll();
    return $result[0][&#39;c&#39;];
  }
  public function update()
  {
    # 修改
  }
  function delete($value=&#39;&#39;)
  {
    # 删除
  }
  public function query($tab_name,$tj=&#39;&#39;)//表名称和条件
  {
    $sth = $this->db->prepare(&#39;SELECT * FROM &#39;.$tab_name.&#39; &#39;.$tj);
    // echo &#39;SELECT * FROM &#39;.$tab_name.&#39; &#39;.$tj;
    $sth->execute();
    $result = $sth->fetchAll();
    return $result;
  }
}
// $db=new SqliteDB();
// $res=$db->insert(&#39;log&#39;,&#39;ip,urls,datetimes&#39;,&#39;"127.0.0.1","www.baidu.com","2012-12-12 00:00:00"&#39;);//添加案例
// $res=$db->query(&#39;log&#39;);//查询案例
// $res=$db->total(&#39;log&#39;);//查询案例
// print_r($res);
// foreach ($res as $key => $row) {
// echo $row[&#39;urls&#39;];
// }
?>