JPA - @Column (unique=true) - What is really point of having 'unique' attribute?

Question

Suppose I am having \'subject\' table

CREATE TABLE subject (id int PRIMARY KEY, name VARCHAR(255) **UNIQUE**)

and associated Mapped Object,

Answer 1

unique=true in @Column annotation will be used only in DDL generation, it doesn't have any impact during runtime. The actual uniqueness checks happens in the database.