Adding Data to the Database with PHP Form

Following on from my last post http://www.shaungill.co.uk/2009/03/first-things-first-connecting-to-the-database/ I’ve got round to writing the form to enter data into the MySql database using a really simple form. I’ll post the code first and then make a few comments about it (the code still uses the db_config.php file I wrote last time)…

index.php

<body>

<h1>Hello World!!</h1>
<form action="post.php" method="post">
  <input type="text" name="post_string">
  <input type="submit" value="Post">
</form>
</body>
</html>

post.php

<body>
<?php
  $sql="INSERT INTO form_test (text)
  VALUES
  ('$_POST[post_string]')";

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

mysql_close($conn)
?>
Your comment of "<?php echo $_POST["post_string"]; ?>" has been entered into the database!
</body>
</html>

The index.php file is basically the worlds simplest form with one text box with a name of ‘post_string’, and the form then posts to ‘post.php’.

Post.php is where all the action takes place.

$sql=”INSERT INTO form_test (text) - this is building the query string which will put the data we enter from the form into the database
(’$_POST[post_string]‘)”; - takes the data from the form field ‘post_string’ and builds it into the query
if (!mysql_query($sql,$conn)) - now, I’ve been doing my homework and the exclamation mark ! is a php negation operator and basically flips a false value to a true value and vise versa. The mysql_query($sql,$conn) is trying to make a connection to the database, and if it fails will return a value of false, so with the exclamation mark it reads “If running the query fails, then…”
die(’Error: ‘ . mysql_error()); - “… stop the script and give the error message, otherwise…”
echo “1 record added”; - “… tell the nice people that 1 record has been added”
mysql_close($conn) - closes the database connection
Your comment of “<?php echo $_POST["post_string"]; ?>” has been entered into the database! - I added this line for my own peace of mind, I wanted visual confirmation that the text that I had written in the form was actually in the $_POST['post_string'] array.