如何使用PHP和MySQL使用where子句更新表？

Question

I'm working on a website that is supposed to pass data from a form on the page and use PHP to update a students table on the server. The condition I'm trying to work on now is Modifying data, so it should be able to update data on the server, but it does not...

Any help or advice you guys can offer will be greatly appreciated. Thanks in advance.

Here is my code:

<?php

date_default_timezone_set('America/New_York');

$connection = mysql_connect("hostaddress","DBname","password");

            // Check connection
if (!$connection)
{
            echo "Connection failed: " . mysql_connect_error();
}
            else
{
                //select table
                mysql_select_db("DBname");
                echo "Database Found! <br>";

                $query = "UPDATE students
                          SET firstName = $_POST[firstName],
                              lastName = $_POST[lastName]
                          WHERE StudentID = $_POST[StudentID]";

                $res = mysql_query($query);

                if ($res)
                {
                   echo "<p>Record Updated<p>";
                }   
                else
                {
                   echo "Problem updating record. MySQL Error: " . mysql_error();
                }
            }

            mysql_close($connection);
        ?>

I keep getting this error:

Database Found! Problem updating record. MySQL Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' lastName = , WHERE Stud' at line 2

PS: I already have the students table created with some data. I can access the table and modify it using the terminal and an identical mysql query like the one above but still no luck. Also, I have changed the host address, database name, and password in my code on purpose (just in case someone asks).

Ouput of echo $query

UPDATE fall14_bmora013.students SET firstName = , lastName = 
WHERE StudentID = 890

Answer 1

Obvious, you have a syntax error (an extra , before WHERE ) in your UPDATE statement as pointed below

UPDATE students SET firstName = $_POST[firstName],
lastName = $_POST[lastName], <-- remove this extra comma
WHERE StudentID = $_POST[StudentID] 

EDIT:

Check whether your form element really named as firstName and lastName ? check the spelling. I doubt the names are different than what you are referring in code.

Answer 2

You wrote it yourself: MySQL Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' lastName = , WHERE Stud' at line 2

Print the query string, it's not what you expect it to be.

Ps You should probably escape your inputs in order to avoid sql-injectiion.

Also, please note you should not use mysql_ functions anymore. read the warning in the following page: http://php.net/manual/en/function.mysql-query.php

Answer 3

Once try this...

$query = "UPDATE students SET firstName ='".$_POST['firstName']."', lastName ='".$_POST['lastName']."' WHERE StudentID = '".$_POST['StudentID']."'";