Question

what is row types of row​

Answer 1

That's what row types are for. That's what they do: a more "flexible" type. In OCaml, there are two main uses of row types: objects and polymorphic variants. In terms of algebra, objects give you "row product" and polymorphic variants "row sum".

Answer 2

The %ROWTYPE attribute provides a record type that represents a row in a database table. The record can store an entire row of data selected from the table or fetched from a cursor or cursor variable. Fields in a record and corresponding columns in a row have the same names and datatypes.