How do I update the database using php?

Question

Here is my first UPDATE query in which i am updating the date, but it is not happening. I made sure that the query is not successful by checking the no of updated rows.

    $ddline = $_POST['deadline_sem'];
    $ex=explode('T', $ddline);
    $date="$ex[0] $ex[1]";
    $deadline=date("Y-m-d H:i:s",strtotime($date));
    echo $deadline;
    $qry1="UPDATE admin SET RegDeadline='$deadline' where username='root'";
    if(mysql_affected_rows()>=0)
        echo "Success";
    else
        echo "Unsuccesull";

Answer 1

Possible way why your code is not working

1) No database connection code.

2) Missing execute statement mysql_query($qry1);

Your code is open for sql injection

Use mysql_real_escape_string() before update into database.

$deadline=mysql_real_escape_string($deadline);
$qry1="UPDATE admin SET RegDeadline='$deadline' where username='root'";
mysql_query($qry1);// execute statement
if(mysql_affected_rows()>=0)
       echo "Success";
else
     echo "Unsuccesull";

Note:- mysql is deprecated instead use PDO or mysqli