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changing select box on another select box value not working in codeigniter

i have a codeigniter website, where there is a form for user to select category and subcategory, when a user selects category the subcategory dropdown should show accordingly, i did the following code:
public function subcategories() {
$category = $this->input->post('category');
$query = $this->db->query('SELECT name FROM subcategory WHERE parentcategory='.$category);
$data['subcategories'] = $query->result_array();
$this->load->view('homecontroller/subcategories', $data);
echo $category;
}
in subcategories.php
<?php foreach ($subcategories as $c): ?>
<option value="<?php echo $c['name'] ?>"><?php echo $c['name'] ?></option>
<?php endforeach; ?>
and in my view:
$(document).ready(function() {
$('#sl_countries').change(function() {
$('#sl_cities').load("<?php echo site_url('index.php/homecontroller/subcategories') ?>", {
category: $(this).val()
});
});
});
<div class="form-group col-md-6">
<label for="inputEmail4">Product Category</label>
<select id="sl_countries" class="form-control" name="cname" aria-label="Default select example">
<?php
foreach($listcategory as $val){
echo '<option value="'.$val->name.'">'.$val->name.'</option>';
}?>
</select>
</div>
<div class="form-group col-md-6">
<label for="inputEmail4">Sub Category</label>
<select class="form-control" name="sname" id="sl_cities"></select>
</div>
however this is not working, i get an error like below when i checked the console:
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 1
SELECT name FROM subcategory WHERE parentcategory=
can anyone please tell me what is wrong here, thanks in advance

use this way:-
jQuery Ajax code :-
<script>
$(document).ready(function(){
$('#country').change(function(){
var country_id = $('#country').val();
if(country_id != '')
{
$.ajax({
url:"<?php echo base_url(); ?>dynamic_dependent/fetch_state",
method:"POST",
data:{country_id:country_id},
success:function(data)
{
$('#state').html(data);
$('#city').html('<option value="">Select City</option>');
}
});
}
else
{
$('#state').html('<option value="">Select State</option>');
$('#city').html('<option value="">Select City</option>');
}
});
});
</script>
Controller Code :-
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class Dynamic_dependent extends CI_Controller {
function fetch_state()
{
if($this->input->post('country_id'))
{
echo $this->dynamic_dependent_model->fetch_state($this->input->post('country_id'));
}
}
}
?>
Model Code :-
<?php
class Dynamic_dependent_model extends CI_Model
{
function fetch_state($country_id)
{
$this->db->where('country_id', $country_id);
$this->db->order_by('state_name', 'ASC');
$query = $this->db->get('state');
$output = '<option value="">Select State</option>';
foreach($query->result() as $row)
{
$output .= '<option value="'.$row->state_id.'">'.$row->state_name.'</option>';
}
return $output;
}
}
?>
View Code :-
<div class="form-group">
<select name="country" id="country" class="form-control input-lg">
<option value="">Select Country</option>
<?php
foreach($country as $row)
{
echo '<option value="'.$row->country_id.'">'.$row->country_name.'</option>';
}
?>
</select>
</div>
<br />
<div class="form-group">
<select name="state" id="state" class="form-control input-lg">
<option value="">Select State</option>
</select>
</div>

PHP query of columns with value from <select> MySQL

I am trying to create a list populated with the columns from a table previously selected from another list of tables. But, I can't get the query to work.
I've appended a sample of my code that is not working. If i replace ".$search_query." with a table name it works. But, I want it to use the table selected by the user.
<!-- Table Select -->
<form name="myform" action="" method="post">
<select id="parentTable_{{$index}}" name="parentTable_{{$index}}" ng-model="parentTable_$index" type="selectable" onchange="submitform();">
<option style="display:none" value="users">select a table</option>
<?php
$count=1;
$sel_query="SHOW TABLES";
$result = mysqli_query($con,$sel_query);
while($row = mysqli_fetch_assoc($result)) { ?>
<option value="<?php echo $row["Tables_in_yamanagolddb"]; ?>"><?php echo $row["Tables_in_yamanagolddb"]; ?></option>
<?php $count++; } ?>
</select>
</form>
<!-- Index reference -->
<?php $search_query = mysqli_real_escape_string($con, $_POST['parentTable_{{$index}}']); ?>
<!-- Field Select -->
<select ng-model="parentField_$index" type="selectable">
<option style="display:none" value="">select a field</option>
<?php
$count=1;
$sel_query="select * from information_schema.columns where table_name = '".$search_query."' and table_schema = 'yamanagolddb'";
$result = mysqli_query($con,$sel_query);
while($row = mysqli_fetch_assoc($result)) { ?>
<option value="<?php echo $row["COLUMN_NAME"]; ?>"><?php echo $row["COLUMN_NAME"]; ?></option>
<?php $count++; } ?>
</select>
<script>
function submitform()
{
document.myform.submit();
}
</script>

How to show selected option in select tag of html?

I am using a select tag from html to show some list. Now when I select one of the option from select tag, I want to load the form again and by the selected option I am running another query and showing the values of another query in another select tag.
Its working properly after selecting any option I am posting a type from which I am getting another data in another select tag, but when I click suppose option TSgt and the form reloads with the TSgt type data, but the option selected in select tag shows as MSgt which is not the one I selected.
If I don't check if the $type is set in _POST array and just show the select tag without an select value like follow :
<option value="1">SSgt</option>
<option value="2">TSgt</option>
<option value="3">MSgt</option>
Then, default selected value shows SSgt,I want to show the value in select tag which user has selected.
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>MCQ Questions</title>
</head>
<body>
<?php
session_start();
$dbh = new PDO('mysql:host=174.75.54;dbname=handbook', 'airman', 'airman');
$type = $_POST['type'];
$question = $_SESSION["question"];
$optionA = $_SESSION["opt1"];
$optionB = $_SESSION["opt2"];
$optionC = $_SESSION["opt3"];
$optionD = $_SESSION["opt4"];
$ans = $_SESSION["ans"];
$chapter = $_SESSION["chapter"];
?>
<form method="post" action="mcq.php" enctype="multipart/form-data">
<p> Enter the question :</p> <input name="question" type="text"> <br><br>
Select question type :
<select name="type" id="type" onchange="this.form.submit()">
<?php if(isset($_POST['type']))
{ ?>
<option value="1" selected=<?=($type==1?"checked":"");?>>SSgt</option>
<option value="2" selected=<?=($type==2?"checked":"");?>>TSgt</option>
<option value="3" selected=<?=($type==3?"checked":"");?>>MSgt</option>
</select>
<?php
}
else
{
?>
<option value="1">SSgt</option>
<option value="2">TSgt</option>
<option value="3">MSgt</option>
</select>
<?php
}
?>
<br><br>
<?php if(isset($optionA))
{ ?>
<p> Enter options :</p>
Enter option A : <input name="opt1" type="text" value = "<?php echo $optionA?>"</input> <br><br>
<?php
}
else{
?>
<p> Enter options :</p>
Enter option A : <input name="opt1" type="text"> <br><br>
<?php
}
?>
Enter option B : <input name="opt2" type="text"> <br><br>
Enter option C : <input name="opt3" type="text"> <br><br>
Enter option D : <input name="opt4" type="text"> <br><br>
Select correct answer :
<select name="ans" id="type">
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
<option value="D">D</option>
</select>
<br><br>
Select Chapter :
<select name="chapters" id="chapters">
<?php
if(isset($_POST['type']))
{
$stmt = $dbh->prepare("SELECT * FROM chapters where type = :type");
$stmt->bindParam("type", $type);
$stmt->execute();
$results = $stmt->fetchall(PDO::FETCH_ASSOC);
if(count($results > 0)){
foreach($results as $row):?>
<option value="<?php echo $row['id'];?>"><?php echo $row['title'];?></option>
<?php
endforeach;
}else{?>
<option value="0">No data found</option>
<?php
}
}
else{
$stmt = $dbh->prepare("SELECT * FROM chapters where type = 1");
$stmt->execute();
$results = $stmt->fetchall(PDO::FETCH_ASSOC);
if(count($results > 0)){
foreach($results as $row):?>
<option value="<?php echo $row['id'];?>"><?php echo $row['title'];?></option>
<?php
endforeach;
}else{?>
<option value="0">No data found</option>
<?php
}
}
?>
</select> <br><br>
<input type="submit" value = "Submit">
</form>
</body>
</html>
<?php
// escape post variables
$question = $_POST['question'];
$option1 = $_POST['opt1'];
$option2 = $_POST['opt2'];
$option3 = $_POST['opt3'];
$option4 = $_POST['opt4'];
$ans = $_POST['ans'];
$chapter = $_POST['chapters'];
if(!empty($ans) and !empty($question) and !empty($option1) and !empty($option2) and !empty($option3) and !empty($option4) and !empty($type) and !empty($chapter))
{
$stmt = $dbh->prepare("INSERT INTO questions (question,answer_a,answer_b,answer_c,answer_d,answer,type,chapterId) VALUES (?, ?, ?, ?, ?, ?, ?,?)");
$stmt->execute(array($question, $option1, $option2, $option3, $option4, $ans,$type,$chapter));
if ($dbh->lastInsertId())
{
echo 'Question submitted.';
echo 'Upload another question.';
session_destroy();
}
else
{
echo 'Question could not submit.';
}
}
else{
$_SESSION["question"] = $question;
$_SESSION["chapter"] = $chapter;
$_SESSION["ans"] = $ans;
$_SESSION["opt1"] = $option1;
$_SESSION["opt2"] = $option2;
$_SESSION["opt3"] = $option3;
$_SESSION["opt4"] = $option4;
echo 'Fill all fields.';
}
?>
I dont know what is going wrong here. Can anyone help me out please?
Thank you.

selected=checked is wrong. selected is enough.
The syntax is <option value="1" selected>SSgt</option>
Change the code to
<option value="1" <?php echo($type==1?"selected":"");?>>SSgt</option>
<option value="2" <?php echo($type==2?"selected":"");?>>TSgt</option>
<option value="3" <?php echo($type==3?"selected":"");?>>MSgt</option>

Multiple Options/MYSQL Records to input box

I wondered if anyone would be able to help me with this as I just can't for the life of me, get it to work.
any help would be most appreciated.
Thanks in advance
$('#options').change(function () {
var optionname=$(this).find('option:selected').attr('data-value');
var optionprice=$(this).find('option:selected').attr('data-price');
$('#optionname').val(optionname);
$('#optionprice').val(optionprice);
});
<select name="options[]" id="options" class="form-control" required>
<option value="">Select Option</option>
<?php
$results99 = $mysqli->query("SELECT * FROM productoptions WHERE productid = '$prod_id' AND cat = 1");
while($rows99 = $results99->fetch_assoc()) {
?>
<option data-value="<?php echo $rows99['optionname']; ?>" data-price="<?php echo $rows99['price']; ?>"><?php echo ucwords(strtolower($rows99['optionname'])); ?> (+<?php echo $rows99['price']; ?>)</option>
<?php
//$results99->free();
}
?>
</select>
<?php } ?>
<input type="text" name="optionname" id="optionname" />
<input type="text" name="optionprice" id="optionprice" />
I just can't get it to work properly

Dynamic Dropdowns POST

I'm trying to post the values that I get from each dropdown menu, this is an n-level, however I'm going to use them maximum of 3. How can I post every value i get from each selection?
<?php
include('dbcon.php');
if($_REQUEST)
{
$id = $_REQUEST['parent_id'];
$query = "select * from ajax_categories where pid = ".$id;
$results = #mysql_query( $query);
$num_rows = #mysql_num_rows($results);
if($num_rows > 0)
{?>
<select name="sub_category" class="parent">
<option value="" selected="selected">-- Sub Category --</option>
<?php
while ($rows = mysql_fetch_assoc(#$results))
{?>
<option value="<?php echo $rows['id'];?>"><?php echo $rows['category'];?></option>
<?php
}?>
</select>
<?php
}
else{echo '<label style="padding:7px;float:left; font-size:12px;">No Record Found !</label>';}
}
?>
http://www.99points.info/2010/12/n-level-dynamic-loading-of-dropdowns-using-ajax-and-php/

change the select option of your like this
<select name="sub_category" class="parent">
<option value="" selected="selected">-- Sub Category --</option>
while ($rows = mysql_fetch_assoc(#$results))
{?>
echo '<option value="'.$row['id'].'">'.$rows['category'].'</option>';
<?php
}?>
</select>
<?php
}
else{echo '<label style="padding:7px;float:left; font-size:12px;">No Record Found !</label>';}
}
</select>