Question

I have an HTML form which submits values to the following PHP file, which inserts them into a MySQL database:

<?php
  $con = mysql_connect("*","*","*");
  if (!$con)
    {
    die('Could not connect: ' . mysql_error());
    }

  mysql_select_db("*", $con);

  $sql="INSERT INTO scores (hometeam, awayteam, result)
  VALUES
  ('" . mysql_real_escape_string($_POST['hometeam']) . "',
   '" . mysql_real_escape_string($_POST['awayteam']) . "',
   '" . mysql_real_escape_string($_POST['result']) . "')";

  if (!mysql_query($sql,$con))
    {
    die('Error: ' . mysql_error());
    }
  echo "1 record added";

  mysql_close($con);
?>

Sometimes an input field in the HTML form will be left empty and in this case I do not want anything inserted into the database. I want the value to remain NULL. At the moment when I fill in my form like this:

Home team: Blue team
Away team: [empty]
Result: Won

The following is inserted into my database:

Home team: Blue team
Away team: ‘ ‘
Result: Won

What I want to be inserted/not inserted is:

Home team: Blue team
Away team: NULL
Result: Won

I’ve hunted hours for a solution. Can anyone help? Thank you.

Answer 1

You can use the NULLIF function from mysql database. What it does is, it takes 2 parameters and return null if they are same. So basically you can change your code to be like following:

  $sql="INSERT INTO scores (hometeam, awayteam, result)
  VALUES
  (NULLIF('" . mysql_real_escape_string($_POST['hometeam']) . "', ''),
   NULLIF('" . mysql_real_escape_string($_POST['awayteam']) . "', ''),
   NULLIF('" . mysql_real_escape_string($_POST['result']) . "', ''))";

It will basically check if the entered value is ”(empty string), and if that’s the case, it would instead save NULL in the database. You can even trim leading or trailing spaces from your variables before passing onto NULLIF, so if someone only enters spaces in your input boxes, it still saved NULL.

Also, as Michael said, it would be safer and better if you move on to PDO or mysqli extension. Hope my answer helps.