Array result returns null

Question

• I need it from the option selected on <select>, me check in the bank what is related to this option. I did this from way that follows below, but in part $p_id = $result['p_id'];, no return, I have already used this array association code other times and it worked.

• I also need that all remain hidden until the moment of choice of <option>, after display what I did, with the records. I do not know the that is wrong, but I accept suggestions for solution and thank you from now on.

                    <div class="form-group">
                      <div class="col-sm-3">
                        <label for="exampleInputEmail1">Cliente</label>
                        <select class="form-control m-b-10" required="required" name="e_id" charset="utf-8">
                          <option>Selecione o cliente</option>
                            <?php
                              $select  = "SELECT e_id, nome FROM pessoas"; 
                              $result  = mysqli_query($conexao, $select);
                              while($exibe = mysqli_fetch_assoc($result)){
                                $e_id = $exibe['e_id'];
                                echo '<option  charset="utf-8" value = '. $e_id . '>' . $exibe['nome'] . '</option>';
                              }                                    
                              mysqli_free_result($result); 
                            ?>                     
                        </select> 
  
                      </div>                                  
                    </div>
                    </form>
                    <!--<button name="salvar" class="btn btn-success" onclick="showElement();">Pesquisar</button>-->
                    <div id="dados" class="form-group" onload="hideElement();">                                                       
                          <?php
                          if ($e_id <> '') {
                            $select  = "SELECT p_id FROM itens WHERE e_id = '$e_id'";  
                            $result  = mysqli_fetch_assoc(mysqli_query($conexao, $select));
                            $p_id  = $result['p_id'];
                            $select2 = "SELECT descricao where p_id = '$p_id'";
                            $resulta = mysqli_query($conexao, $select2);          
                            if (mysqli_num_rows($resulta) > 0){                            
                            echo '<table class="table table-hover" >
                                <thead>
                                  <tr>
                                    <th>Descrição</th>
                                </tr>
                            </thead>
                            <tbody>
                              <tr>';
                              while($exibe = mysqli_fetch_assoc($resulta)){ 
                                  $p_id  = $exibe['p_id'];
                                  echo '<tr>';  
                                    echo '<td value = "">' . $exibe['descricao']      . '</td>';                   
                            }
                          }else{
                            echo '<label for="exampleInputPassword1">Não há registros</label>'; 
                          } 
                        }else{
                          echo '<label for="exampleInputPassword1">Não há registros</label>';
                        }             
                        mysqli_free_result($result);  
                        mysqli_free_result($resulta);                                                                              
                          ?>                                     
                    </tr>
                </tbody>
            </table>
  

Answer 1

I need from the option selected in select, I see in the bank what is related to this option.

No way to use the PHP in the client-side (@Andersoncarloswoss).

For that reason, one can:

• Make a second page that showcase the description according to the id method-tested get form;
• Submit the form at the event change of <select> with a request AJAX;
• Show request data (contents of second tab) on a div;

Understanding this, let’s go to the code:

index php.

<!DOCTYPE html>
<html>
    <head>
        <title></title>
        <script src="https://code.jquery.com/jquery-3.2.1.min.js" type="text/javascript"></script>

        <script type="text/javascript">

            $(document).ready(function(){
                $('#slcClientes').on('change', function() {
                    var dados = jQuery( '#fmrClientes' ).serialize();
                    $.ajax({
                        type: "POST",
                        url: $('#fmrClientes').attr('action'),
                        data: dados,
                        success: function(data) {
                            $('#dvAlvo').html(data);
                        }
                    });
                });
            });

        </script>

    </head>
    <body>

        <form id="fmrClientes" action="get_obs.php" method="post">
            <select id="slcClientes" name="cl_id">
                <option selected="selected" disabled="disabled">Selecione:</option>
            <?php

                $conexao = mysqli_connect("host", "usuário", "senha", "banco de dados"); // CONFIGURE!!!
                $res = mysqli_query( $conexao, "SELECT `ClID`, `ClNome` FROM `clientes` LIMIT 0,10;"); // LIMITEI PARA 10 REGISTROS - SOMENTE PARA FINS DE TESTE
                if(mysqli_num_rows($res) > 0)
                {
                    while( $cl = mysqli_fetch_assoc($res) )
                    {
                        echo "<option value=" . $cl['ClID'] . ">" . $cl['ClNome'] . "</option>";
                    }
                }

            ?>
            </select>
        </form>

        <div id="dvAlvo">
            <!-- ALVO DA REQUISIÇÃO AJAX -->
        </div>

    </body>
</html>

get_obs.php

<?php

    $conexao = mysqli_connect("host", "usuário", "senha", "banco de dados"); // CONFIGURE!!!
    $id = $_POST['cl_id'];
    $res = mysqli_query( $conexao, "SELECT `ClOBS` FROM `clientes` WHERE `ClID` = '" . $id . "';");
    $desc = mysqli_fetch_assoc($res);
    echo nl2br( htmlspecialchars( $desc['ClOBS'] ) );

?>

Table structure customers:

+---------+--------------+------+-----+---------+----------------+
| Field   | Type         | Null | Key | Default | Extra          |
+---------+--------------+------+-----+---------+----------------+
| ClID    | int(5)       | NO   | PRI | NULL    | auto_increment |
| ClNome  | varchar(150) | YES  |     | NULL    |                |
| ClObs   | text         | YES  |     | NULL    |                |
+---------+--------------+------+-----+---------+----------------+

Remember to set the variable $conexao in both archives!

I also need that all remain hidden until the moment of the choice of option, after displaying what I did, with the records.

As the div target is empty, the content will only be shown on it when selecting some option from select. The trigger is on line 7 of index.php.

The code I developed is 100% functional. Tested with PHP 7. However, I treat the description as observing in my code.

I didn’t care about form validation. Do it yourself. This code is for guidance purposes.

Tip if there are many customers: Instead of making one select showing all registered customers, recommend you create a input[type=text] with autocomplete of jQuery.