Update not working i can't find my error - php

Question

My update script is not working.. I don't know what im missing..
but i can't update the table ... Went to w3school to know about the update in php but still it wont work...
-noob coder-
<?php
include 'Core/init.php';
protect_page();
include 'Includes/Overall/overallheader.php';
?>
<h1>Update School Year and Semester</h1>
<?php
$con=mysqli_connect("localhost","root","1234","database3");
// Check connection
$sy = $_POST['school_year'];
$sem = $_POST['semester'];
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
if ( isset($_POST['submit'] ) )
{
$sql = "UPDATE `activesys` SET `activeschoolyear` = '$sy' AND `activesemester` = '$sem'";
$exec = mysql_query($sql) or die(mysql_error());
}
?>
<form action="" method="post">
<ul>
<li>
School Year:<br />
<input type="text" name="school_year">
</li>
<li>
Semester:<br />
<input type="text" name="semester">
</li>
<li>
<input type="submit" value="submit">
</li>
</ul>
</form>
<?php
include 'Includes/Overall/overallfooter.php';
?>

Answer 1

Even though its not directly realated:
Please make sure to escape Request data that you load from $_POST or $_GET by using mysql_escape_string . Otherwise it would be easy to inject SQL in your query, which would allow to run harmfull sql in your system, like deleting the database or manipulating the data.
http://en.wikipedia.org/wiki/SQL_injection

Answer 2

You have missed where condition in update query .. try this
UPDATE table_name
SET column1=value, column2=value2,...
WHERE some_column=some_value
$sql = "UPDATE `activesys` SET `activeschoolyear` = '$sy' AND `activesemester` = '$sem'" WHERE some_column=some_value;

Answer 3

First, you mix mysqli and mysql. Second, mysql_query/mysqli_query have two parameters. Third, your sql is not right.
So, change your $exec = mysql_query($sql) or die(mysql_error())
to $exec = mysqli_query($con,$sql) or die(mysqli_error($con));
change your sql to :
$sql = "UPDATE `activesys` SET `activeschoolyear` = '$sy' , `activesemester` = '$sem'";
but you didn't have a where condition here, if in your table you have set an
anto-increment key and set it to primary key, you could add some condition end of you sql,otherwise it will
update all your records.
$sql = "UPDATE `activesys` SET `activeschoolyear` = '$sy' , `activesemester` = '$sem' where id={$id}"
$id is one recod from you table.
this should work for you excute an update..

Answer 4

Try using this :
1) use "action" attribute of the tag
<form action="<?php echo $_SERVER['PHP_SELF'] ?>" method="post">
2) check whether your form has beensubmitted :
if(isset($_POST['submit']))
3) Use WHERE condition in your sql query. You final query should look like this :
<?php
if(isset($_POST['submit']))
{
$con = mysqli_connect("localhost","root","1234","database3");
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
exit();
}
$query = "
UPDATE `activesys`
SET `activeschoolyear` = '$sy',`activesemester` = '$sem'
WHERE `columnName` = `columnValue`
";
mysqli_query($con,$query);
}