📄️ One-to-One (oto)
A one-to-one relation means each row on one side has at most one matching row on the other side.
📄️ One-to-Many (otm)
A one-to-many relation means a single row on one side has many matching rows on the other.
📄️ Many-to-One (mto)
A many-to-one relation is the reverse of one-to-many. Many rows on this side, one row on the other.
📄️ Many-to-Many (mtm)
A many-to-many relation joins two tables through a third one — the junction table.