mysql_fetch_array() error in php mysql [duplicate]

Question

Here is the code of : select_class.php

 <?php 

    $get_userclass_query="select courseandbatch from studentdetails group by courseandbatch          ";
    $get_userclass_result=mysql_query($get_userclass_query);
    while($get_userclass_row=mysql_fetch_array($get_userclass_result))
   {?>
    <option value="<?php echo $get_userclass_row['courseandbatch']; ?>"><?php echo     $get_userclass_row['courseandbatch']; ?></option>
    <?php echo $get_userclass_row['courseandbatch']; ?><?php
}
?>

code:sis.php
 Batch:<input type="text"  /><select name="search"  style="width:100px; height:20px;" >
    <?php
    include '../select_class.php';
    ?>
     </select> 

When I execute this page, I have the following error:

mysql_fetch_array() expects parameter 1 to be resource, boolean given in C:\xampp\htdocs\apnacar\select_class.php on line 5

How can I fix this ?

Answer 1

 <?php 

    $get_userclass_query="select courseandbatch from studentdetails group by courseandbatch          ";
    $get_userclass_result=mysql_query($get_userclass_query);
    if($get_userclass_result === FALSE) {
     die(mysql_error()); 
   }
    while($get_userclass_row=mysql_fetch_array($get_userclass_result))
   {?>
    <option value="<?php echo $get_userclass_row['courseandbatch']; ?>"><?php          echo $get_userclass_row['courseandbatch']; ?></option>
    <?php echo $get_userclass_row['courseandbatch']; ?><?php
}
?>