Updating data in DataBase with PHP

Question

I have a simple script that should Update variable in a column where user login equals some login.

<?PHP
$login = $_POST['login'];
$column= $_POST['column'];
$number = $_POST['number'];

$link = mysqli_connect("localhost", "id3008526_root", "12345", "id3008526_test");

$ins = mysqli_query($link, "UPDATE test_table SET '$column' = '$number' WHERE log = '$login'");
if ($ins)
    die ("TRUE");
else
    die ("FALSE");
?>

but it doesn't work. It gives me - FALSE. One of my columns name is w1 and if I replace '$column' in the code with w1 it works fine. Any suggestions?

Justinas · Accepted Answer · 2017-11-22 13:54:47Z

4

Simply remove quotes: '$column' = should be $column =

Your code is open for SQL Injection, use prepared statements.

answered Nov 22, 2017 at 13:54

Justinas

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miraoui.bob · Accepted Answer · 2017-11-22 13:57:18Z

1

change this "UPDATE test_table SET '$column' = '$number' WHERE log = '$login'"

to this "UPDATE test_table SET '".$column."' = ".$number." WHERE log = '".$login."'"

answered Nov 22, 2017 at 13:57

miraoui.bob

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simandsim · Accepted Answer · 2017-11-22 13:55:45Z

0

It's possible that your error is to do with the $column being set as a string with single quotation marks? Because it returns false, it suggests that you have a MySQL error of some sort.

To find out what the error message is, on your else block, rather than dying with a "FALSE" message, try use mysqli_error($link) - this should give you your error message

answered Nov 22, 2017 at 13:55

simandsim

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1 Comment

Justinas Over a year ago

There is no error in SQL, just returned 0 updated rows, because 'string' != 'another_string'.

Marc · Accepted Answer · 2017-11-22 14:32:08Z

If removing the quotes surrounding the $column doesn't work, you could try the PDO method. Here's the snippet:

function insertUser($column, $number, $login) {
try 
{ 
    $connect = getConnection(); //db connection
    $sql = "UPDATE test_table SET $column = '$number' WHERE log = '$login'";
    $connect->exec($sql); 
    $connect = null; 
 } catch (Exception $ex) { 
     echo "EXCEPTION : Insert failed : " . $ex->getMessage(); 
 } 
 }

function getConnection() { 
 $servername = "localhost"; 
 $dbname = "my_db"; 
 $username = "root"; 
 $password = "12345"; 

 try { 
     $connection = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password); 
     $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 
 } catch (Exception $ex) { 
     echo "EXCEPTION: Connection failed : " . $ex->getMessage(); 
 } 

     return $connection; 
 }

Regarding $number, I'm not sure the datatype for the $number whether quotes or not is needed so experiment with or without quotes to see which one works.

And the getConnection() function is in separate PHP file where it will be included in any PHP files that calls for database connection.

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