--- create-vk-users

CREATE TABLE vk_users (
  id          BIGINT PRIMARY KEY,
  client_id   BIGINT NOT NULL REFERENCES clients (id),
  first_name  VARCHAR,
  last_name   VARCHAR,
  screen_name VARCHAR,
  sex         INTEGER,
  photo       VARCHAR
);

CREATE UNIQUE INDEX vk_users_client_id_uniq
  ON vk_users (client_id);
