OrderGroup
Tableorder_group, id prefix og. The aggregate over the per-seller orders
created from a single cart.
Relations:
orders (one-to-many through the order_group_order link table),
cart (read-only, via cart_id).
seller_count and total are marked computed(). They hold no value on the
row and are aggregated from the group’s child orders each time it’s read. See
Computed totals.