Question

I wonder why I get errors with that code? Can Someone help?
My class is to get some information from database using nested methods,suppose I get an empty query

<?php
class db {
 public function __construct(){
 if(mysql_connect("localhost","root","0000")){
     mysql_select_db("myblog");

 }else{
     echo mysql_error();
 }

 }

   public function select($row){
      $sql="SELECT".$row;
      return $this;
   }

   public function from($table){
      $sql.="FROM".$table;
      return $this;
   }

   public function where($condition){
     $sql.="WHERE".$condition;
      return $this;
   }

}
$ddb=new db;
$qq=$ddb->select("*")->from("news")->where("id='1'");
$query=  mysql_query($qq);
while($row=mysql_fetch_object($query)){
    echo $row->title;
}
?>

Answer 1

You have to define __toString() special method to use your object as a string:

class db {

    private $sql = '';

    public function __construct() {
        if (mysql_connect("localhost", "root", "0000")) {
            mysql_select_db("myblog");
        } else {
            echo mysql_error();
        }
    }

    public function select($row) {
        $this->sql = "SELECT ".$row;
        return $this;
    }

    public function from($table) {
        $this->sql .= " FROM ".$table;
        return $this;
    }

    public function where($condition) {
        $this->sql .= " WHERE ".$condition;
        return $this;
    }

    public function __toString() {
        return $this->sql;
    }

}

$ddb = new db();
$qq = $ddb->select("*")->from("news")->where("id='1'");
$query = mysql_query($qq);
while ($row = mysql_fetch_object($query)) {
    echo $row->title;
}