How to auto increment bill no - php

Question

Design page code:
<input type="text" class="form-control " placeholder="Bill.No"name="billno" id="AcNo" value="" required>
Ajax code:
<script type="text/javascript">
$(document).ready(function(){
$.ajax({
type: "POST",
url: "<?php echo base_url();?>TipUp_Loan/get_AcNo",
data:{id:$(this).val()},
datatype:'json',
success: function (data) {
var res = jQuery.parseJSON(data);
$("#AcNo").val(res);
alert(ok);
}
});
});
</script>
Controller code:
public function get_AcNo()
{
$query = $this->db->query('SELECT MAX(no) AS `AcNo` FROM `salesbill` ORDER BY no DESC LIMIT 1')->row_array();
//print_r($query);
if($query['AcNo'] == "")
{
$message = 1;
}
else
{
$message = $query['AcNo']+1;
}
echo json_encode ($message);
}
My problem is the bill no is constantly showing 2 how to auto increment the bill no once the form is submited

Answer 1

Try this one
$(document).ready(function(){
$.ajax({
type: "POST",
url: "TipUp_Loan/get_AcNo",
data:{id:$(this).val()},
datatype:'json',
success: function (data) {
$("#AcNo").val(data);
alert(ok);
}
});
});
public function get_AcNo()
{
$query = $this->db->query('SELECT MAX(no) AS `AcNo` FROM `salesbill` ORDER BY no DESC LIMIT 1')->row_array();
//print_r($query);
if ($query['AcNo'] == ""){
$message = 1;
} else {
$message = $query['AcNo']+1;
}
echo $message;
}

Answer 2

edit it like this
<script type="text/javascript">
$(document).ready(function(){
$.ajax({
type: "POST",
url: "<?php echo base_url();?>TipUp_Loan/get_AcNo",
data:{id:$(this).val()},
datatype:'json',
success: function (data) {
$("#AcNo").val(data);
alert('ok');
}
});
});
</script>
public function get_AcNo()
{
$query = $this->db->query('SELECT MAX(no) AS `AcNo` FROM `salesbill` ORDER BY no DESC LIMIT 1')->row_array();
//print_r($query);
if ($query['AcNo'] == ""){
$message = 1;
} else {
$message = $query['AcNo']+1;
}
echo $message;
}

Answer 3

You can try this sql query:
$query = $this->db->query('SELECT MAX(no) AS "AcNo" FROM "salesbill"')->row_array();
or you can try this query as well:
$query = $this->db->query('SELECT count(no) AS "AcNo" FROM "salesbill"')->row_array();