从字符串rtrim中删除最后一个逗号

Question

Can't seem to get rtrim to work and I don't understand why:

$array = array("top" => array("one" => "inner one", "two" => "inner two"));

foreach (array_keys($array) as $key) {
  $form[$key] = array();
  $sql = "INSERT INTO $key SET ";
  foreach (array_keys($array[$key]) as $field) {
    array_push($form[$key], $field);
    $sql .= $field." = '".$array[$key][$field]."',";
  }
}
  rtrim($sql,',');
  $sql .= ";";

Why would this not get rid of the last comma?

it keeps printing out this:

INSERT INTO top SET one = 'inner one',two = 'inner two',;

Answer 1

You have to assign the rtrim to $sql like that:

$sql = trim($sql, ",");