How can we handle NULL values stored in a MySQL table by using PHP script?

We can use the if...else condition in PHP script to prepare a query based on the NULL value. To illustrate it we are having the following example −

Example

In this example, we are using the table named ‘tcount_tbl’ having the following data −

mysql> SELECT * from tcount_tbl;
+-----------------+----------------+
| tutorial_author | tutorial_count |
+-----------------+----------------+
|      mahran     |       20       |
|      mahnaz     |      NULL      |
|       Jen       |      NULL      |
|      Gill       |       20       |
+-----------------+----------------+
4 rows in set (0.00 sec)

Now, the following is a PHP script that takes the value of ‘tutorial_count’ from outside and compares it with the value available in the field.

<?php
   $dbhost = 'localhost:3036';
   $dbuser = 'root';
   $dbpass = 'rootpassword';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);

   if(! $conn ) {
      die('Could not connect: ' . mysql_error());
   }

   if( isset($tutorial_count )) {
      $sql = 'SELECT tutorial_author, tutorial_count FROM tcount_tbl
         WHERE tutorial_count = $tutorial_count';
   } else {
      $sql = 'SELECT tutorial_author, tutorial_count FROM tcount_tbl
         WHERE tutorial_count IS $tutorial_count';
   }

   mysql_select_db('TUTORIALS');
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die('Could not get data: ' . mysql_error());
   }

   while($row = mysql_fetch_array($retval, MYSQL_ASSOC)) {
      echo "Author:{$row['tutorial_author']} <br> ".
         "Count: {$row['tutorial_count']} <br> ".
         "--------------------------------<br>";
   }
   echo "Fetched data successfully
";
   mysql_close($conn);
?>