PHP爲什麼If/Else語句在While循環中不起作用？

Question

這是我的代碼，我不知道爲什麼if/else語句不工作

$user_id = $_POST['user_id']; 

$strSQL = "SELECT chat.user_id,max(date) max_date ,user.user_id,user.firstname,user.lastname,user.picture 
    FROM (select from_user_id as user_id,date,isread from chat 
     WHERE to_user_id = '$user_id' 
     Union select to_user_id as user_id,date,isread from chat WHERE from_user_id = '$user_id') as chat join user on user.user_id = chat.user_id 
    where user.status != 'block' group by chat.user_id order by max_date DESC"; 
     $chatdata = array(); 
     $objQuery = mysql_query($strSQL); 

     while($row = mysql_fetch_assoc($objQuery)){ 
      $frduser_id = $row['user_id']; 
      $firstname = $row['firstname']; 
      $lastname = $row['lastname']; 
      $picture = $row['picture']; 
      $strSQL2 = "SELECT isread from chat WHERE to_user_id = '$user_id' and from_user_id = '$frduser_id' 
         ORDER BY date DESC LIMIT 1"; 

      //array_push($chatdata, $row); 
     $objQuery2 = mysql_query($strSQL2); 
     if (empty($objQuery2)) { 
      $row2 = 1; 
      $result = array_merge($row, $row2); 
      array_push($chatdata,$result); 
     }else{ 
     $row2 = mysql_fetch_assoc($objQuery2); 
     $result = array_merge($row, $row2); 
     array_push($chatdata,$result); 
    } 
} 

Answer 1

您可以使用mysql_num_rows進去結果的行數。

$objQuery2 = mysql_query($strSQL2); 
$objQuery2Rows = mysql_num_rows($strSQL2); 

if ($objQuery2Rows < 1) { 
     $row2 = 1; 
     $result = array_merge($row, $row2); 
     array_push($chatdata,$result);  
}else{ 
     $row2 = mysql_fetch_assoc($objQuery2); 
     $result = array_merge($row, $row2); 
     array_push($chatdata,$result); 
}