How to prevent logging when the php sql server page is updated

Dear, I would like you to help me, I'm doing an insert with php and sql server for which you register correctly but the problem is that when I update the page you register how I can avoid that.

this is my code:

 <table class="table">
                                                            <tr>
                                                                <td>Año Electivo</td>
                                                                <td> <select name="AnioID" class="form-control">
                                                                    <option value="0">--Seleccionar--</option>
                                                                    <?php
                                                                        $sql = "EXEC AGE_Mantenimiento_AnioLectivo 1,'','','','','' "   ;

                                                                    $result = sqlsrv_query($conn,$sql) or die("Couldn't execut query");
                                                                    while ($data=sqlsrv_fetch_array($result, SQLSRV_FETCH_ASSOC)){
                                                                        echo '<option value="'.$data['nAnioID'].'">';
                                                                        echo $data['Anio']; 
                                                                        echo "</option>";
                                                                    }

                                                                    ?>
                                                                </select></td>
                                                            </tr>
                                                            <tr>
                                                                <td>Descripción</td>
                                                                <td><textarea class="form-control" rows="5" id="Descripcion" name="txtdescripcioninstitucion"  placeholder="Ingrese una descripión" ></textarea></td>
                                                            </tr>
                                                            <tr style="visibility: hidden;">
                                                                <td>Numero de Carpetas</td>
                                                                <td><input type="number" name="txtnumerocarpetas" placeholder="Ingrese el Numero de Carpetas" class="form-control"></td>
                                                            </tr>
                                                            <tr>
                                                                <td colspan="2" class="text-center">
                                                                    <button type="submit" name="Guardar" class="btn btn-primary">Guardar</button>
                                                                </td>
                                                            </tr>
                                                        </table>
<?php


if(isset($_POST['Guardar'])){


    $t2=$_POST['AnioID'];
    $t3=$_POST['txtdescripcioninstitucion'];



    $sql ="
    EXEC AGE_Mantenimiento_Institucion 2,'$t2','$t3'
    ";

    $params = array('$t1','$t2','$t3');

    $stmt = sqlsrv_query($conn, $sql, $params);
    sqlsrv_close($conn);

    if( $stmt === false ) {


      echo "<script language=\"JavaScript\">\n"; 
      echo "alert('EL USUARIO NO EXISTE');\n"; 
      echo "</script>";  
  }else{
      echo "<script>";
      echo "reset();";
      echo "</script>";

  }
}

?>