Help With Array!!!

Ok so here it goes: I have an array that is attached to a web form. It's function is to ask the user what she has been involved in. There are 3 rows with 4 columns each. The user is required to fill out at least one row but not all three.
Here is the problem. When I test it out all three rows are entered into the database wether they hold information or not. How do I get the parser to recognize when a row is blank and ignore it before the info is inserted into the database?

Here is the PHP Code for the Array
foreach($_POST['Activity'] as $row=>$Act)
{
$Activity=($Act);
$Position=($_POST['Position'][$row]);
$StartDate=($_POST['StartDate'][$row]);
$EndDate=($_POST['EndDate'][$row]);

if (!empty($Act)) {
$involv = "INSERT INTO Involvement (Activity, Position, StartDate, EndDate)
VALUES ('$Activity','$Position','$StartDate','$EndDate')";
};

Thanks in advance

 

You could use regex, which I've never used before, and I'd certainly be interested in the solution you will embark on, because I need to implement a similar system in my intranet project.

 

if (!empty($Act) && !empty($Position) && !empty($StartDate) && !empty($EndDate)) {

}

PHP:

?

 

Thanks, I've never heard of empty

 

The other is isset()

 

I use that