if a value is changed... what function do i use?

[eMonk]

I have an update form where users can update their info.

 

If they update their email address, I want "to do" something.

 

For example:

 

if(isset($email) )
{
do something
}

 

However the isset function won't work in my case because $email is always NOT NULL so it will always perform this action which won't be necessarily.

 

What  function do I use to check if $email was changed?

[eMonk]

Something like this?

 

if $email = $email
{
perform normal query
} else {
perform a modified query
}

[The Little Guy]

use empty

[Fadion]

When the form is submitted, check if the email isn't empty (via $_POST or $_GET) and if not, update the data in database. There's no need to compare the form value with the actual value from database, because if the email isn't empty, it is supposed to be changed.

 

<?php
$email = trim($_POST['email']);
if ($email != '') {
     $results = mysql_query("UPDATE users SET email='$email' WHERE user_id=10");
}
?>

 

Hope I got it right, anyway.

[The Little Guy]

When the form is submitted, check if the email isn't empty (via $_POST or $_GET) and if not, update the data in database. There's no need to compare the form value with the actual value from database, because if the email isn't empty, it is supposed to be changed.

 

<?php
$email = trim($_POST['email']);
if ($email != '') {
     $results = mysql_query("UPDATE users SET email='$email' WHERE user_id=10");
}
?>

 

Hope I got it right, anyway.

 

the empy function is better

[eMonk]

email will always be not empty.

 

For example, let's say John wants to update his email address.

 

The update form loads john@somewhere.com into the form but then he changes it to johnny@somewhere.com. If this is the case then I'll need to update the members database as well with his new email address. Sure I can always perform this action and override it everytime but I don't think it's necessarily?

[eMonk]

Or maybe just not have the form fetch their email address into the email text field and if they fill this field in then I'll update the members database as well? Then I can use the isset function and let them know only to fill in this textbox if they want to update their email address and display their old one below it.

[eMonk]

Ah, guess I will override it every time a form is updated since the other values are being overwritten as well.

[Pikachu2000]

If the value of a field value in the UPDATE query is the same as what's in the field already, MySQL won't do anything with it anyhow.

 

http://dev.mysql.com/doc/refman/5.0/en/update.html

[eMonk]

Thanks for the info Pikachu2000 and everyone else that commented.

 

Question:

 

What's the difference between (if any):

 

if (isset($email))

 

and

 

if (empty($email))

[eMonk]

Nevermind. I see a comparison in example #1 at:

 

http://ca3.php.net/empty

 

I learned a new function today. Thanks The Little Guy!