not understanding mysqli_fetch_array - php

Question

So i guess i don't understand this i am a very newbie to coding in general. I have searched and can't find a good enogh explanation to get it to work in my situatation. I need to fill a table from a fetch command then update each result with an input of information into a new column. Here is the code i have:
This fills the table:
echo "<table border='1'>
<tr>
<th>Envelope</th>
<th>Budget</th>
<th>Amount</th>
</tr>";
while($row = mysqli_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['envelopename'] . "</td>";
echo "<td>" . $row['envelopebudget'] . "</td>";
?><td><input type="text" name="budgetamount"></td><?php;
echo "</tr>";
}
echo "</table>";
?>
<input type="submit">
And this writes the input for budgetname into the column budgetname:
$paycheckname = mysqli_real_escape_string($con, $_POST['paycheckname']);
$budgetamount = mysqli_real_escape_string($con, $_POST['budgetamount']);
$envelopename = mysqli_real_escape_string($con, $_POST['envelopename']);
}
$sql="UPDATE envelopes SET $paycheckname='$budgetamount' WHERE envelopename ='$envelopename'";
if (!mysqli_query($con,$sql)) {
die('Error: ' . mysqli_error($con));
}
Right now it just doesn't write anything. I have used echo var_dump($envelopename)."<br>"; and echo var_dump($budgetamount)."<br>"; to try and see what it is doing but $envelopename is always blank. Thanks for any help you can provide.

Answer 1

only <input> , <textarea>, <select> and <button> are submitted to the server in a form
If you want to re-submit some static values create some hidden inputs
while($row = mysqli_fetch_array($result)) {
echo "<input type='hidden' value='$row[envelopename]' name='envelopename'/>";
echo "<input type='hidden' value='$row[envelopebudget]' name='envelopebudget'/>";
echo "<tr>";
echo "<td>" . $row['envelopename'] . "</td>";
echo "<td>" . $row['envelopebudget'] . "</td>";
?><td><input type="text" name="budgetamount"></td><?php;
echo "</tr>";
}
echo "</table>";
But your next issue will be that you're creating the elements in a loop so you'll have multiple inputs with the same name
<tr>
<input type='hidden' value='envName1' name='envelopename'/>
<input type='hidden' value='envBudget1' name='envelopename'/>
<td>envName1</td>
<td>envBudget1</td>
<td><input type="text" name="budgetamount"></td>
</tr>
<tr>
<input type='hidden' value='envName2' name='envelopename'/>
<input type='hidden' value='envBudget2' name='envelopename'/>
<td>envName2</td>
<td>envBudget2</td>
<td><input type="text" name="budgetamount"></td>
</tr>
so you must submit as an array
while($row = mysqli_fetch_array($result)) {
echo "<input type='hidden' value='$row[envelopename]' name='envelopename[]'/>";
echo "<input type='hidden' value='$row[envelopebudget]' name='envelopebudget[]'/>";
echo "<tr>";
echo "<td>" . $row['envelopename'] . "</td>";
echo "<td>" . $row['envelopebudget'] . "</td>";
?><td><input type="text" name="budgetamount[]"></td><?php;
echo "</tr>";
}
echo "</table>";
and at the server end process as an array
foreach ($_POST['budgetamount'] as $budgetamount){
echo $budgetamount. '<br>';
}

Answer 2

suppose the form rendered looks like this:
<tr>
<input type='hidden' value='envName1' name='envelopename[]'/>
<input type='hidden' value='envBudget1' name='envelopebudget[]'/>
<td>envName1</td>
<td>envBudget1</td>
<td><input type="text" name="budgetamount[]"></td>
</tr>
<tr>
<input type='hidden' value='envName2' name='envelopename[]'/>
<input type='hidden' value='envBudget2' name='envelopebudget[]'/>
<td>envName2</td>
<td>envBudget2</td>
<td><input type="text" name="budgetamount[]"></td>
</tr>
<tr>
<input type='hidden' value='envName3' name='envelopename[]'/>
<input type='hidden' value='envBudget3' name='envelopebudget[]'/>
<td>envName3</td>
<td>envBudget3</td>
<td><input type="text" name="budgetamount[]"></td>
</tr>
when the user hits submit the $_POST that arrives at newpaycheck.php will look like:
$_POST
['envelopename']{
[0]=>'envName1',
[1]=>'envName2',
[2]=>'envName3'
},['envelopebudget']{
[0]=>'envBudget1',
[1]=>'envBudget2',
[2]=>'envBudget3'
},['budgetamount']{
[0]=>'someValueEnteredByUser',
[1]=>'anotherValueEnteredByUser',
[2]=>'yetAnotherValueEnteredByUser'
}
so you can do something like this:
foreach ($_POST['envelopename'] as $envelopename){
$arrayIndex = array_search($envelopename,$_POST['envelopename']);
$envelopebudget = $_POST['envelopebudget'][$arrayIndex];
$budgetamount= $_POST['budgetamount'][$arrayIndex];
$paycheckname = mysqli_real_escape_string($con, $envelopebudget);
$budgetamount = mysqli_real_escape_string($con,$budgetamount);
$envelopename = mysqli_real_escape_string($con,$envelopename);
$sql="UPDATE envelopes SET $paycheckname='$budgetamount' WHERE envelopename ='$envelopename'";
if (!mysqli_query($con,$sql)) {
die('Error: ' . mysqli_error($con));
}
}