Php inserts data into database with empty values before form is submitted?

Question

I'm trying to use this code from this site which inserts empty fields into a database when the page is initially loaded and when the form's fields are filled out and submitted, then another batch of data is inserted into the database (MySQL). How this behavior can be avoided?

<html>
<body>

<form action="insert.php" method="post">
Firstname: <input type="text" name="firstname">
Lastname: <input type="text" name="lastname">
Age: <input type="text" name="age">
<input type="submit">
</form>

</body>
</html> 
<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

$sql="INSERT INTO Persons (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";

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

mysqli_close($con);
?>

when page load, code run. code inserts values even when empty - solution, check form submitted before insert — user557846
– user557846, Commented Feb 24, 2014 at 0:59

enterx · Accepted Answer · 2014-02-24 01:05:35Z

3

<html>
<body>

<form action="insert.php" method="post">
Firstname: <input type="text" name="firstname">
Lastname: <input type="text" name="lastname">
Age: <input type="text" name="age">
<input type="submit" name="submit" value="submit" />
</form>

</body>
</html> 
<?php
if($_POST['submit']){
  $con=mysqli_connect("example.com","peter","abc123","my_db");
  // Check connection
  if (mysqli_connect_errno())
    {
      echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }

    $sql="INSERT INTO Persons (FirstName, LastName, Age)
      VALUES
      ('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";

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

  mysqli_close($con);
}
?>

You have to check if($_POST['submit']) variable has a value set.

also you need to add some value and a name to your input type="submit" html element

<input type="submit" name="submit" value="Submit!" />

answered Feb 24, 2014 at 1:05

enterx

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4 Comments

Predrag Beocanin Over a year ago

Also might not suggest a junior to input $_POST data directly into the database #justsaying

mickmackusa Over a year ago

if($_POST['submit']) is not the way to check if an array element exists or not. PHP will complain. See Fabio's answer which used isset().

enterx Over a year ago

@mickmackusa ofc you can add all sorts of error handling and over bloated frameworks with validation DTOs etc but that was not the question here.

mickmackusa Over a year ago

Let's not ramp into ridiculousness. All I am saying is that one condition is not covering an obvious possible scenario. You can waste time arguing, or you can edit your answer to implement a very sensible check. Then these comments can be removed. I use old pages to close new pages -- that is why I need old answers to be of high quality advice. Otherwise, the whole page cannot be used as a dupe target.

Fabio · Accepted Answer · 2014-02-24 01:00:52Z

2

You need to check for isset() of your submit button before inserting otherwise it will insert an empty row at each load, so add it

</body>
</html> 
<?php

if(isset($_POST['submit']))
{
     $con=mysqli_connect("example.com","peter","abc123","my_db");

     //all your code here
}

Note that your submit button is missing name so change it to

<input type"submit" name="submit">

answered Feb 24, 2014 at 1:00

Fabio

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Comments

user3316397 · Accepted Answer · 2014-02-24 00:59:44Z

1

Put your insert code jn an if statement like:

If (isset($_post)) { Code here }

answered Feb 24, 2014 at 0:59

user3316397

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