Question

Is there any profit to limit datatype while declaring a table if data length limit is known beforehand?

create table "user"."table" (
    ...
    "is_there_any_profit" number (1, 0)
)

vs

create table "user"."table" (
    ...
    "is_there_any_profit" number
)

Answer 1

Technically not, all numbers are stored same way (mantissa + exponent). The profit is in business logic rules implementation. If you expect to store whole numbers into database, it is good idea to enforce this by setting correct datatype (e.g. NUMBER(10,0)). You declare, that other values are invalid.