how to echo Drop down value from data base in edit page - php

Question

I want to echo database value for the drop down in edit mode. but in edit page it doesn't show the previously selected drop down value. now i want to echo database values to the drop down. how can i do it. My view controller and model are below. Please any one can help me.
View
<!--//Address-->
<tr><td><?php echo '<label for="heading" class="col-sm-0 control-label">Address </label>';?></td>
<td class="col-lg-10">
<?php
$data = array(
'name' => 'address',
'value' => $post->address,
'class' => 'form-control',
'style' => 'width:140%',
'placeholder' => 'Address of Your Site'
);
echo form_input($data);
echo '<br>';
?>
</td>
</tr>
<!--//Address-->
<?php foreach ($single as $post):?>
$attributes = 'class = "form-control" id = "client" style="width:140%; height:35px;"';
$buildings = array('-SELECT-'=>'-SELECT-', 'House'=>'House', 'Building Complex'=>'Building Complex', 'Commercial Building'=>'Commercial Building', 'Hotel'=>'Hotel','Hospital'=>'Hospital' );
echo form_dropdown('building', $buildings, $post->building,set_value('building'), $attributes);
?>
Controller
function edit_single(){
$id = $this->uri->segment(3);
//load project details according to relevent id
$data['single'] = $this->project_registration_details->show_pro_id($id);
$this->load->view('client/project_registration_edit_view',$data);
}
Model
function show_pro_id($id){
$this->db->select('*');
$this->db->from('project_registration');
$this->db->join('client', 'client.client_id = project_registration.reg_client_id');
$this->db->where('project_registration.id',$id);
$query = $this->db->get();
$result = $query->result();
return $result;
}

Answer 1

Use
set_value('building',$post->building)
in your selected part of form_dropdown function.
Try..
echo form_dropdown('building', $buildings,set_value('building',$post->building), $attributes);
Updated Answer
<?php foreach($single as $post) { ?>
<select name="building" class = "form-control" id = "client" style="width:140%; height:35px;">
<?php
$buildings = array('-SELECT-'=>'-SELECT-', 'House'=>'House', 'Building Complex'=>'Building Complex', 'Commercial Building'=>'Commercial Building', 'Hotel'=>'Hotel','Hospital'=>'Hospital' );
foreach($buildings as $key => $building) { ?>
<option value="<?php echo $key; ?>" <?php echo set_select('building', $post->building); ?>><?php echo $building; ?></option>
<?php } ?>
</select>
<?php } ?>