Question

I use play! framework 2.0 and postgresql.
in my db there is users table and every user ofcourse has a unique id.
so I defined it as serial.

my question is: how to represent a field which it’s data type is serial
in my java project.

p.s. I understood play! framework uses Hibernate annotation

Answer 1

From the PostgreSQL documentation, the SERIAL type is equivalent to an ìnteger` with a sequence, so:

CREATE TABLE tablename (
    colname SERIAL
);

is equivalent to specifying:

CREATE SEQUENCE tablename_colname_seq;
CREATE TABLE tablename (
    colname integer DEFAULT nextval('tablename_colname_seq') NOT NULL
);

The @Id JPA annotation on the Long type will provide a sequence (equivalent to AUTO_INCREMENT in MySQL).

So, in you class, just use:

@Id
public Long id;