带逗号的单独PHP数组的数据

Question

based on a query:

  $query = $db->query("SELECT id, email, status, enviados FROM 
  contactos LIMIT 0,500");

where I get emails and store them in an array I want to separate them and print them by commas and then put them in a variable, where the result is something like:

$ variable = a1, a2, a3;

I try to do with implode but it does not work, I was already seeing the other issues but I can not find a solution

this is my code

$query = $db->query("SELECT id, email, status, enviados FROM 
contactos LIMIT 0,500");

$count = $query->num_rows;


while($row = mysqli_fetch_array($query)){
    $datos_seleccionados[] = array(
        'emails' => $row['email']
    );
}   

for ($i = 0; $i <= $count; $i++) {
    echo implode(",", $datos_seleccionados[$i]);
}

Answer 1

You need to do it in this way

$datos_seleccionados = [];
while($row = mysqli_fetch_array($query))
{
  $datos_seleccionados[] = $row['email'];
}
echo implode(",", $datos_seleccionados);