PHP Bootstrap multi select options - php

Question

In my code I am using PHP which populates the bootstrap multi selectpicker from MySQL database but the problem is it only selects the last option instead of multiple options, I don't know what I am missing in it? Here is my my code
function MultiBindCombo($tablenames, $columnnames1, $columnnames2, $comboname, $selectedopt) {
global $conn;
$sql="SELECT ". $columnnames1. ", " . $columnnames2 . " FROM ". $tablenames;
$result = mysqli_query($conn, $sql);
if( ! $result ) {
echo mysql_error();
exit;
}
echo '<select class="selectpicker form-control" data-live-search="true" name="' . $comboname . '" multiple="multiple">';
$array = explode(',', $selectedopt);
while ($row=mysqli_fetch_array($result)) {
foreach ($array as $select_option){
if($row[$columnnames1] == $select_option) {
$print_selected = 'selected';
} else {
$print_selected = '';
}
echo $select_option;
}
echo '<option data-tokens="' . $row[$columnnames1] . '" value="' . $row[$columnnames1] . '"' .$print_selected. '>' . $row[$columnnames2] . '</option>';
}
echo '</select>';
}

Answer 1

To get all selected values in a multiselect you need to use name attribute with []:
echo '<select class="selectpicker form-control" data-live-search="true" name="' . $comboname . '[]" multiple="multiple">';
After that you can iterate over $_POST[$comboname] with a foreach.
Update:
Let's look closer to your code here:
while ($row=mysqli_fetch_array($result)) {
foreach ($array as $select_option){
// You iterate over every value of array, so in the end
// `$print_selected` is defined depending on value of the
// last `$select_option`
if($row[$columnnames1] == $select_option) {
$print_selected = 'selected';
} else {
$print_selected = '';
}
// remove this. Why you echo `$select_option`?
echo $select_option;
}
echo '<option data-tokens="' . $row[$columnnames1] . '" value="' . $row[$columnnames1] . '"' .$print_selected. '>' . $row[$columnnames2] . '</option>';
}
Rewrite it as:
while ($row=mysqli_fetch_array($result)) {
$print_selected = '';
foreach ($array as $select_option){
if($row[$columnnames1] == $select_option) {
$print_selected = 'selected';
// break `foreach` as you found the right item
break;
}
}
// if right item is not found - `$print_selected` is empty
echo '<option data-tokens="' . $row[$columnnames1] . '" value="' . $row[$columnnames1] . '"' .$print_selected. '>' . $row[$columnnames2] . '</option>';
}