UnboundReference function
A reference that refers to a record from another table.
Unlike Reference, it doesn't create a constraint. Rather, it is developer's job to ensure it. It is useful if you prefer not to create an index, and can access with other key(s).
otype
- it is useless but for documentation purpose
Implementation
SqlType UnboundReference({String? otype, String constraint = notNull})
=> SqlType("text", constraint: constraint);