/*
    *    @function 解析where条件数组
    *    @param $where where条件数组
    *    @return array
    *    @notice 只支持简单的条件语句
    *    $where的数据结构如下
        $where=array(
            array("id",">","3"),
            array("id","<","10"),
        );
    */
    public function analyzeWhere($where){
        $arr=array();
        if(!is_array($where)||empty($where)){
            $arr["str"]="";
            $arr["value_arr"]=array();
        }
        else{
            
            $where_arr=array();
            $where_value_arr=array();
            foreach($where as $key=>$value){
                if(count($value)==3){
                    if($value[1]=="in"){
                        if(empty($value[2])){
                            continue;
                        }
                        else{
                            $where_arr[]= "`".$value[0]."` ".$val[1]." ('".implode("','",$value[2])."') ";
                        }
                    }
                    else if($value[1]=="like"){
                        $where_arr[]="`".$value[0]."` ".$value[1]." '%".$value[2]."%' ";
                    }
                    else{
                        
                        $where_arr[]="`".$value[0]."` ".$value[1]." ? ";
                        if(is_numeric($value[2])){
                            $where_value_arr[]=$value[2];
                        }
                        else{
                            $where_value_arr[]='\''.$value[2]."\'";
                        }
                    }
                }
            }
            $arr["str"]=!empty($where_arr) ? " WHERE ".implode(" and ",$where_arr) : "";
            $arr["value_arr"]=$where_value_arr;
        }
        return $arr;
    }
    
    /*
    *    @function 解析group数组
    *    @param $group group数组
    *    @return array
    *    @notice group by 后跟字段，所以不需要占位符
        $group数据格式如下
        $group=array(
            "id","ct",
        );
    */
    public function analyzeGroup($group){
        $arr=array();
        if(!is_array($group)||empty($group)){
            $arr["str"]="";
        }
        else{
            $groupArr=array();
            foreach($group as $key=>$value){
                $groupArr[]=$value;
            }
            $str_group=implode(",",$groupArr);
            $arr["str"]=" GROUP BY ".$str_group;
        }
        $arr["value_arr"]=array();
        return $arr;
    }

    /*
    *    @function 解析having数组
    *    @param $having having数组
    *    @return array
    *    @notice
        $having数据格式如下
        $having=array(
            "id","=","6",
        );
    */
    public function analyzeHaving($having){
        $arr=array();
        if(!is_array($having)||empty($having)){
            $arr["str"]="";
        }
        else{
            $str_having="";
            foreach($having as $key=>$value){
                $str_having.=$value." ";
            }
            $arr["str"]=" HAVING ".$str_having;
        }
        $arr["value_arr"]=array();
        return $arr;
    }

    /*
    *    @function 解析order数组
    *    @param $order order数组
    *    @return array
    *    @notice order by 后跟字段所以不需要占位符
        $order数据格式如下
        $order=array(
            "id","ct",
        );
    */
    public function analyzeOrder($order){
        $arr=array();
        if(!is_array($order)||empty($order)){
            $arr["str"]="";
        }
        else{
            $orderArr=array();
            foreach($order as $key=>$value){
                $orderArr[]=$value;
            }
            $str_order=implode(",",$orderArr);
            $arr["str"]=" ORDER BY ".$str_order;
        }
        $arr["value_arr"]=array();
        return $arr;
    }

    /*
    *    @function 解析limit数组
    *    @param $limit limit数组
    *    @return array
    *    @notice $limit数据格式如下
        $limit=array(
            "id","ct",
        );
    */
    public function analyzeLimit($limit){
        $arr=array();
        if(!is_array($limit)||empty($limit)){
            $arr["str"]="";
            $arr["value_arr"]=array();
        }
        else{
            $limitArr=array();
            $limitValueArr=array();
            foreach($limit as $key=>$value){
                $limitArr[]="?";
                $limitValueArr[]=$value;
            }
            $str_limit=implode(",",$limitArr);
            $arr["str"]=" LIMIT ".$str_limit;
            $arr["value_arr"]=$limitValueArr;
        }
        return $arr;
    }
    
    /*
    *    @function 释放结果集
    */
    public function free(){
        if($this->stmt){
            $this->stmt=null;
        }
    }

    /*
    *    @function 断开连接
    */
    public function close(){
        if($this->conn){
            $this->conn=null;
        }
    }
}
$dbhelper=new pdo_dbhelper();
$result=$dbhelper->readAll("category",array("name"),array("where"=>array(array("id","=","3"))));
$dbhelper->free();
$dbhelper->close();
print_r($result);
?>