function to delete older sqlite records when the limit is reached

PHP

// this will delete records over the specified number if run.
// it will keep the latest $records_to_keep number and delete older ones.
public function delete_over($records_to_keep = 1000) {
  $db_table_name = $this->db_table_name;
  $sql = "DELETE FROM $db_table_name WHERE ROWID IN (SELECT ROWID FROM $db_table_name ORDER BY ROWID DESC LIMIT -1 OFFSET $records_to_keep)";
  $result = $this->db->query($sql);
}

// example run on keywords class
$keywords->delete_over($records_to_keep = 1000);