INSERT requires SERIAL column?

Hello,

I've got a table with these columns:

user_id      SERIAL       CONSTRAINT pk_user_auth_user_id PRIMARY KEY,
email        VARCHAR(64)    NOT NULL UNIQUE        ,
password     VARCHAR(16)    NOT NULL        ,
status       SMALLINT    NOT NULL DEFAULT 1

But when I tried using the following INSERT statement I got an error about not being able to parse the input.

INSERT INTO user_auth VALUES ('foo@example.com', 'password', 1);

psql:../data/user_auth.dat:13: ERROR:  pg_atoi: error in "foo@example.com": can't parse "foo@example.com"

So this indicates that an integer was expected as the first value.

In order to get it to do what I want I had to use this:

INSERT INTO user_auth VALUES (nextval('user_auth_user_id_seq'), 'foo@example.com', 'password', 1);

Question:
Is this really necessary or am I missing something?
I thought specifying SERIAL columns is not neccessary in INSERT statements.

Thank you,
Otis

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