尝试更新数据库中的条目

I'm trying to update a record in my database using the code below. I'm trying to change the product name but I am getting the following error:

Could not update data: Unknown column 'Earrings' in 'field list'

Code:

<?php
if(isset($_POST['update']))
{
    $dbhost = 'databasehost';
    $dbuser = 'username';
    $dbpass = 'password';
    $conn = mysql_connect($dbhost, $dbuser, $dbpass);

        if(! $conn )
        {
            die('Could not connect: ' . mysql_error());
        }

        $ProductsID = $_POST['ProductsID'];
        $ProductsName = $_POST['ProductsName'];

        $sql = "UPDATE Products ".
           "SET ProductsName = $ProductsName ".
           "WHERE ProductsID = $ProductsID" ;

        mysql_select_db('databasename');
        $retval = mysql_query( $sql, $conn );
        if(! $retval )
        {
            die('Could not update data: ' . mysql_error());
        }
        echo "Updated data successfully
";
        mysql_close($conn);
}
else
{
?>

The query should be

$sql = "UPDATE Products ".
       "SET ProductsName = '$ProductsName' ".
       "WHERE ProductsID = $ProductsID" ;

You forgot to wrap $ProductName with quotations. Don't forget to do so when dealing with string values.

You want something like this:

ProductsName = '$ProductsName'

Also, be sure to escape that input, else you'll be subjected to SQL injections.

You are not sanitizing your data, so there is a good chance that your query could break depending on the value submitted, not to mention it leaves your database wide open for an attacker to manipulate via SQL Injection.

Please do not use mysql_ functions, as they are depricated. You should be using prepared statements, please see PDO and mysqli.

As for your answer, you need to put 'quotes' around the $variable

Your are trying to set the ProductsName to an existing column, add quotes to let sql interpret a value:

$sql = "UPDATE Products ".
       "SET ProductsName = '$ProductsName' ".
       "WHERE ProductsID = $ProductsID" ;