Problem with fetch_all (), does not get rows

The next time you use the mysqli or PDO libraries to work with your databases, since mysql is currently not used much, but when you are working on accessing a specific field of the table and putting it into a div , or something dynamically, I do it with PDO, and I leave you my way of doing it

              try
               {
        $bbdd_conection = new PDO("mysql:host=localhost;dbname=mi_tabla", "root", "");
                  if
                    ($bbdd_conection->errorCode())
                   {
                    die("Fallo al conectar con la base de datos");
                   }else {
     $bbdd_conection->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
               $bbdd_conection->exec('SET CHARACTER SET UTF8');
               $stm = "SELECT * nombre_tabla"
               $objeto = $bbdd_conection->prepare($stm);
               $objeto->execute();
               $resultado_demi_tabla = $objeto->fetchAll(PDO::FETCH_OBJ);
               foreach($resultado_demi_tabla as $valor){
                   print_r($valor) // usarlo para testear
                   echo $valor->campo1

                   //Con esto podras acceder a cada campo que devuelve el registro de tu tabla, si tu tabla se llama nombre,edad etc con $valor->edad podras ver los resultados y utilizarlos.
               }

               //
                   }
               } catch (PDOException $ex) {
                    echo "Fallo al conectar o enviar una consulta a la base de datos en la linea " . $ex->getLine()
                    . " y el causante del fallo es " . $ex->getMessage() . PHP_EOL;
               }finally{
                   $bbdd_conection = NULL;
               }

            }


        }

>

(Assuming you're using mysqli) Unlike the fetch method, the output of fetch_all is not traversed, but used directly.

<?php

try {
    require_once ('includes/funciones/bd_conexion.php');
    $sql = "SELECT * FROM 'registros'; ";
    $resultado = $conn->query($sql);

    echo "<pre>";
    var_dump($resultado->fetch_all(MYSQLI_ASSOC));
    echo "</pre>";
} catch (Exception $e) {
    $error = $e->getMessage();
}

Beware, the methods are called different in mysqli than in PDO . You did not tell us which one you are using.

I found the solution to the problem, change this code:

<?php while($registros= $resultado->fetch_all(MYSQLI_ASSOC)) { ?>
   #codigo 
<?php } ?>

For this other:

<?php $registros= array() ?>
      <?php while($registro= $resultado->fetch_assoc()) { ?>
            <?php $registros[] = $registro; ?>
      <?php } ?>

In this way I obtained the same result. Clarification: if I am using msqli and also use the fecth_all () directly but it does not work. Thanks everyone for your help. Greetings.