How can we handle NULL values stored in MySQL table using PHP script?-PHP Tutorial-php.cn

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

WBOY

Release： 2023-09-07 18:18:02

forward

922 people have browsed it

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

We can use if...else conditions in PHP scripts to prepare queries based on NULL values. To illustrate this, we use the following example -

Example

In this example, we use a table named 'tcount_tbl' which contains 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)

Copy after login

Now, below is a PHP script that gets the value of 'tutorial_count' from outside and compares it with the value available in the field.

<?php
   $dbhost = &#39;localhost:3036&#39;;
   $dbuser = &#39;root&#39;;
   $dbpass = &#39;rootpassword&#39;;
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);

   if(! $conn ) {
      die(&#39;Could not connect: &#39; . mysql_error());
   }

   if( isset($tutorial_count )) {
      $sql = &#39;SELECT tutorial_author, tutorial_count FROM tcount_tbl
         WHERE tutorial_count = $tutorial_count&#39;;
   } else {
      $sql = &#39;SELECT tutorial_author, tutorial_count FROM tcount_tbl
         WHERE tutorial_count IS $tutorial_count&#39;;
   }

   mysql_select_db(&#39;TUTORIALS&#39;);
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die(&#39;Could not get data: &#39; . mysql_error());
   }

   while($row = mysql_fetch_array($retval, MYSQL_ASSOC)) {
      echo "Author:{$row[&#39;tutorial_author&#39;]} <br> ".
         "Count: {$row[&#39;tutorial_count&#39;]} <br> ".
         "--------------------------------<br>";
   }
   echo "Fetched data successfully</p><p>";
   mysql_close($conn);
?>

Copy after login

The above is the detailed content of How can we handle NULL values stored in MySQL table using PHP script?. For more information, please follow other related articles on the PHP Chinese website!