public Connection::nextId($existing_id = 0)
Retrieves an unique ID from a given sequence.
Use this function if for some reason you can't use a serial field. For example, MySQL has no ways of reading of the current value of a sequence and PostgreSQL can not advance the sequence to be larger than a given value. Or sometimes you just need a unique integer.
Parameters
$existing_id: (optional) After a database import, it might be that the sequences table is behind, so by passing in the maximum exis