Loop through form to update SQL Database - php

Question

I am building a page that writes out a varying number of categories and then, under each category, writes out the units associated with that category. Each category section is a single form with fields that are repeated and named according to what row they belong to. The layout is like this:
Category 1
Unit 1 Update Fields
Unit 2 Update Fields
Unit 3 Update Fields
Submit Button for Category 1
etc.
Each field is named the same thing with the unit number added on the end:
Features1, Features2, Features3, etc.
The total number of rows in a given category is held in the variable $id# where # is the category's ID (ex: $id1, $id2, $id3, etc).
I've got most of this sorted out. However, I want to loop through and perform a SQL query if the form has been changed, and that's where I'm having trouble. At this point, I'm at a loss. Here is a simplified version of my code:
if (isset($_POST['submit'])) {
$form = $_POST['form']; //save which category we're on in a variable.
for ($i = 1; $i <= ${id.$form}; $i++) { //I think the problem is here
$Feature = $_POST['Feature'.$i];
$update = "UPDATE Units
SET Feature ='$Feature'
WHERE ID='$i'";
if (($Feature!=${initialFeature.$i})) {
$updateQuery = mysqli_query($dbc, $update);
}
}
}
How can I make this work? Is there a better way to do this?

Answer 1

The way I would do it is using an array in field names.
<input type="text" name="id[]" value="$foo">
Then on the action page for the form
$id = $_POST['id'];
for($i=0;$i<sizeof($id),$i++){
...//do something here using $id[$i] to select elements in the array
}
I think that is what you're trying to do.

Answer 2

try this
for($i=0; $i<3; $i++)
echo '<input type="text" name="feature[]" value=""/>';
echo '<input type="submit" name="go" value="submit">';
if (isset($_POST['go'])) {
$feature = $_POST['feature'];
if(is_array($feature)){
for ($i = 1; $i <= count($feature); $i++) {
$update = "UPDATE Units
SET Feature ='$feature[$i]'
WHERE ID='$i'";
$updateQuery = mysqli_query($dbc, $update);
}
}else{
$update = "UPDATE Units
SET Feature ='$feature'
WHERE ID='$i'";
$updateQuery = mysqli_query($dbc, $update);
}
}
hope this code can solve your problem