php - Dropdown list is empty

Solution:

Test the success or failure of your query withif (!$result) and usemysql_num_rows() to verify the number of rows returned. Rather thandie(), you can display a better error to your user and possibly render different HTML, rather than just exit the script abruptly.

  mysql_select_db("mydb");  
  $sql = "SELECT state_id, state_code FROM states"; 
  $result = mysql_query($sql);

  // Instead of die(), use a construct like this for better error handling on your page
  if (!$result) {
    // query error
  }     

  if (mysql_num_rows($result) === 0) {
    // No rows returned
  }
  else {
    // Success! Populate your <select> with <option>s
    while($row = mysql_fetch_array($result)){ 
     echo "<option value=\"".$row['state_id']."\">".$row["state_code"]."</option>";   
    }
  }
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UPDATE

Add an empty default option. Make sure itsvalue attribute is not something you would retrieve from your database.

<select name="vers"> 
  <option value='-1'>Choose an option...</option>
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Solution:

Try running the query directly against the database using a tool such as MySql Workbench

SELECT state_id, state_code FROM states
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I suspect there are no results.

UPDATE: Given that 50 results are expected... can you try this version with minor updates and report back on any warnings or errors you can see.

<?php
use error_reporting(E_ALL | E_STRICT); // Development use only!

$link = mysql_connect("localhost:3306", "root", "root") or die ('Error connecting to mysql' . mysql_error());

mysql_select_db("mydb");  

$sql = "SELECT state_id, state_code FROM states;"; 
$result = mysql_query($sql) or die(mysql_error());
?>
<p>  
    <select name="vers">  
    <?php
    while($row = mysql_fetch_array($result)) { 
        echo '<option value="' . $row['state_id'] . '">' . $row['state_code']  . '</option>';
    }  
    ?>  
    </select>
</p>
<?php
mysql_close($link); 
?> 
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Solution:

How can I find out if my query returned any result?

Run your query on your Database Server instead of through PHP and see if it returns any results. If you use shared hosting with MySQL, many hosts provide a phpmyadmin interface that lets you run SQL commands.

Solution:

you can use mysql_num_rows to find out how many elements you have in your$result

Solution:

At first, you should check your table "states". If it is empty, your code is correct. For example, you can use PhpMyAdmin - http://www.phpmyadmin.net. Execute your query with phpMyAdmin