Listing 1. Defining the People Table

CREATE TABLE People (
        person_id      SERIAL      NOT NULL,

        first_name     VARCHAR(20) NOT NULL  CHECK
      (first_name <>
''),
last_name      VARCHAR(20) NOT NULL  CHECK
   (last_name <>''),
        address1       VARCHAR(30) NULL      CHECK
      (address1 <>''),
        address2       VARCHAR(30) NULL      CHECK
      (address2 <>''),
        email          VARCHAR(50) NOT NULL  CHECK
      (email ~'@'),
        city           VARCHAR(30) NULL      CHECK
      (city <>''),
        state          VARCHAR(2)  NULL      CHECK
      (state <>''),
        postal_code    VARCHAR(10) NULL      CHECK
      (postal_code <>''),
        country        VARCHAR(20) NOT NULL  CHECK
      (country <>''),
        comments       TEXT      NULL       CHECK
      (comments <>''),

        PRIMARY KEY(person_id),
        UNIQUE(email)
    );