Edit html + php + jquery items

I have to edit a record series, they are listed in a table (see):

Hereistheimageformabove:

<divclass="control-group">
                <table class="table table-bordered ">
                    <thead>
                    <tr style="backgroud-color: #2D335B">
                        <th>Nome do Envolvido</th>
                        <th>RG</th>
                        <th>Envolvimento</th>
                        <th>Opções</th>
                    </tr>
                    </thead>

                    <tbody>
                    <?php if (!$envolvidos) { ?>
                        <td colspan="5">Ainda sem envolvidos</td>
                    <?php } else {
                        foreach ($envolvidos as $r) { ?>
                                <tr>
                                    <td style="text-align: center">
                                        <input type="hidden" id="id_e" name="id_e"
                                               value="<?php echo set_value('id', $r->id); ?>">
                                        <input class="span9" type="text" id="nome_e" name="nome_e"
                                               value="<?php echo set_value('nome', $r->nome); ?>">
                                    </td>
                                    <td style="text-align: center">
                                        <input class="span6" type="text" id="rg_e" name="rg_e"
                                               value="<?php echo set_value('rg', $r->rg); ?>">
                                    </td>
                                    <td style="text-align: center">
                                        <select style="width: 120px" id="envolvimento_e" name="envolvimento_e"
                                                value="<?php echo set_value('envolvimento', $r->envolvimento); ?>">
                                            <option
                                                value="SOLICITANTE" <?php if ($r->envolvimento == 'SOLICITANTE') echo 'selected' ?>>
                                                Solicitante
                                            </option>
                                            <option
                                                value="AUTOR" <?php if ($r->envolvimento == 'AUTOR') echo 'selected' ?>>
                                                Autor
                                            </option>
                                            <option
                                                value="VITIMA" <?php if ($r->envolvimento == 'VITIMA') echo 'selected' ?>>
                                                Vítima
                                            </option>
                                            <option
                                                value="TESTEMUNHA" <?php if ($r->envolvimento == 'TESTEMUNHA') echo 'selected' ?>>
                                                Testemunha
                                            </option>
                                        </select>
                                    </td>
                                    <td style="text-align: center">
                                        <button type="button" id="enviar" class="btn btn-primary btn-lg"> Editar
                                        </button>
                                    </td>
                                </tr>
                        <?php }
                    } ?>
                    </tbody>
                    <thead>
                    <tr style="backgroud-color: #2D335B">
                        <th>Nome do Envolvido</th>
                        <th>RG</th>
                        <th>Envolvimento</th>
                        <th>Opções</th>
                    </tr>
                    </thead>
                </table>

And I've already tried putting each tr inside a form , the problem that editing only works for the first item of table does not trigger the ajax that sends to controler. See ajax:

jQuery('#enviar').click(function () {
        var id = $('#id_e').val();
        var nome = $('#nome_e').val();
        var rg = $('#rg_e').val();
        var envolvimento = $('#envolvimento_e').val();

        $.post("<?php echo base_url(); ?>index.php/sbp/editarEnvolvido",
            {'id': id, 'nome': nome, 'rg': rg, 'envolvimento': envolvimento},
            function (data) {
                alert(data);
            }, "html");

    });

For better understanding here is the function of the controller that does the editing in the database:

function editarEnvolvido(){
    $id = $_POST['id'];
    $nome = $_POST['nome'];
    $rg = $_POST['rg'];
    $envolvimento = $_POST['envolvimento'];

    if((strcmp($id,"") != 0) && (strcmp($nome,"") != 0) && (strcmp($rg,"") != 0)){
        $data = array(
            'nome'                  => $nome,
            'rg'                    => $rg,
            'envolvimento'          => $envolvimento
        );
        if ($this->sbp_model->edit('envolvidos', $data, 'id', $id) == TRUE) {
            echo 'Salvo com sucesso!';
        } else {
            echo 'Erro ao tentar salvar!';
        }
    } else {
        echo 'Nome e/ou RG deve ser informado!';
    }
}

I'd like to at least understand what's happening other lines do not trigger ajax, and I accept additional suggestions to solve my problem. Thank you in advance!