On-demand paging with PHP POST button and method using PDO

Question

I looked at some sites and saw some things about it, but I’m not getting the logic behind the page on demand.

jQuery(document).ready(function(){
        jQuery('#btnpaginas').click(function(){
            var dados = jQuery( this ).serialize();

            jQuery.ajax({
                type: "POST",
                url: "paginacao.php",
                data: dados,
                success: function(data)
                {
                                $(".paginacao").html(data);
                }
            });

            return false;
        });
    });

<button id="btnpaginas">Carregar mais</button>

PHP

$inicio = 5;

$stmt = $conecta->prepare("select * from postagem order by idpost desc limit $inicio " );
    $stmt->execute();

I know I’m doing it wrong. It already starts with 1 record and when I press the "press more" button it shows the first record, which already had, and four more. Only with this code that I made, it will not load 5 more if I click again, I want to know how to do for whenever I click the button, it show 5 more records to my posting system.

Answer 1

1. HTML/JS Code

   <script type="text/javascript">
   $(document).ready(function(){
     jQuery('#btnpaginas').click(function(){
       var dados = jQuery( this ).serialize();
       jQuery.ajax({
           type: "POST",
           url: "teste.php",
           data: dados,
           success: function(data)
           {
                           $(".paginacao").html(data);
           }
       });
   
       return false;
       });
   });
   </script>
   
   <button id="btnpaginas">Carregar mais</button>
   
   <div class="paginacao"></div>
   

2. PHP code

   <?php 
   
   $numPaginas = 5;
   
   $stmt = $conecta->prepare("select * from postagem order by idpost desc limit $numPaginas " );
   echo $stmt->execute();
   

Answer 2

Your problem is in understanding SQL, more specifically about the "LIMIT" clause. See how it works in the link: https://www.w3schools.com/php/php_mysql_select_limit.asp

To work the way you need to, do the following:

1) on your page, set a variable "PAGE" which will store the page number you want to get the results from. The first results, corresponds to page 0 "zero". Each time you click the PRESS BUTTON increments the variable "PAGE"

2) Whenever you make a request to the server, send page number

To understand the technique I describe, visit the link: http://blog.thiagobelem.net/entendendo-a-paginacao-de-registros-no-mysql

---

# Code

jQuery(document).ready(function(){
var pagina = 0;
jQuery('#btnpaginas').click(function(){
    pagina++;
    var dados = jQuery( this ).serialize();

    jQuery.ajax({
        type: "POST",
        url: "paginacao.php?pagina="+pagina,
        data: dados,
        success: function(data)
        {
            $(".paginacao").html(data);

        }
    });
    return false;
});

PHP

<?php
$itensPorPagina = 10;
$pagina = ( !isset( $_GET['pagina'] ) ? 0 : ((int)$_GET['pagina']) - 1);
$inicio = $pagina * $itensPorPagina;


$stmt = $conecta->prepare("SELECT * FROM postagem ORDER BY idpost DESC LIMIT $inicio, $itensPorPagina " );
$stmt->execute();

I hope I’ve helped