Change mysql column with button

Question

I want to change a mysql column, when I press a button. My current code:

      <?php if ($result = $mysqli->query("SELECT type FROM users WHERE id_user = 2 ")) {

            $r = mysqli_fetch_assoc($result);

            }
        print_r($r);

       if(isset($_POST['d'])){
       $sql = "UPDATE users SET type= 'd' WHERE id_user = 2 ";
       }
        ?>
        <input type="submit" value="d" name="d" />

I want to change of the column "type" which is set a by default, where the id = 2, but when I press the button, nothing happens. What have I done wrong in the if(isset()) ?

EDIT: SOLVED with all respondents:

<?php
if(isset($_POST['d'])){
$var = $_POST['d'];
$sql = "UPDATE users SET `type`= '$var'  WHERE id_user = 2 ";
$mysqli->query($sql) or die($mysqli->error);
}
if(isset($_POST['a'])){
$var = $_POST['a'];
$sql = "UPDATE users SET `type`= '$var'  WHERE id_user = 2 ";
$mysqli->query($sql) or die($mysqli->error);

}
?>
<form action="#" method="POST">
   <input type="text" value="d" name="d"/>
   <input type="submit" value="d"/>
</form>
<form action="#" method="POST">
   <input type="text" value="a" name="a"/>
   <input type="submit" value="a"/>
</form>


<?php

 if ($result = $mysqli->query("SELECT `type` FROM users WHERE id_user = 2 ")) {

    $r = mysqli_fetch_assoc($result);

    }
print_r($r);
print_r($_POST)
?>

Is this inside a <form> tag? When you say "nothing happens" do you mean that nothing happens and the page stays as is, or that the page reloads but without the database action? — Michael Berkowski
– Michael Berkowski, Commented Nov 9, 2016 at 21:10
Yes it is. The only thing that changes, is my url with the end tag "?d=d". The print stays the same with a — pr0cz
– pr0cz, Commented Nov 9, 2016 at 21:14
I inserted the code below and it still stays the same. The page refreshs and the print hasn't changed. If I click on "refresh" manually, an alert pops up, that if I return, the action will be done again.. I am confused. — pr0cz
– pr0cz, Commented Nov 9, 2016 at 21:19
if(isset($_POST['d'])) { $var = $_POST['d']; ... UPDATE users SET type = '$var' WHERE... } . It will be much easier if you used a prepared statement for this. Prepared statements mysqli php.net/manual/en/mysqli.prepare.php — Funk Forty Niner
– Funk Forty Niner, Commented Nov 9, 2016 at 22:10

Funk Forty Niner · Accepted Answer · 2016-11-09 22:16:12Z

2

As I stated in comments: (and besides other comments I left).

Assign a variable to it then pass it in the query and quote it.

if(isset($_POST['d'])) { 

  $var = $_POST['d']; ... UPDATE users SET type = '$var' WHERE... 

}

But do learn to use prepared statements, since you are open to an sql injection:

http://php.net/manual/en/mysqli.prepare.php

answered Nov 9, 2016 at 22:16

Funk Forty Niner

74.2k14 gold badges71 silver badges146 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

rbr94 · Accepted Answer · 2016-11-09 21:35:44Z

2

You need to set the variable in the query like this and print out the value of your select statement inside the if clause. Furthermore as @Patrick Q mentioned TYPE is a mysql keyword and must be enclosed in backticks:

PHP:

if ($result = $mysqli->query("SELECT `type` FROM users WHERE id_user = 2 ")) {
    $r = mysqli_fetch_assoc($result);
    print_r($r);
}

if(isset($_POST['d'])) {
    $sql = "UPDATE users SET `type`= '" . $_POST['d'] . "' WHERE id_user = 2 ";
    $mysqli->query($sql);
}

HTML:

<form action="#" method="POST">
   <input type="text" value="d" name="d"/>
   <input type="submit" value="d"/>
</form>

Pay attention that you really use POST as the method of the form and not GET.

edited Nov 9, 2016 at 21:35

answered Nov 9, 2016 at 21:10

rbr94

2,2874 gold badges27 silver badges40 bronze badges

19 Comments

pr0cz Over a year ago

I will try it! Thanks!

pr0cz Over a year ago

I inserted the code and it still stays the same. The page refreshs and the print hasn't changed. If I click on "refresh" manually, an alert pops up, that if I return, the action will be done again.. I am confused.

rbr94 Over a year ago

@pr0cz I do not quite understand your first query (select). Why do you do this at all?

pr0cz Over a year ago

just to see, what type is already set. So if there are a couple of accounts listed, too see which one is a and which one is d

Barmar Over a year ago

Check for errors from the UPDATE query: $mysqli->query($sql) or die($mysqli->error);

|

Collectives™ on Stack Overflow

Change mysql column with button

2 Answers 2

Comments

19 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

19 Comments

Your Answer

Sign up or log in

Post as a guest

Related