CREATE TABLE contacts (
  id           INTEGER PRIMARY KEY AUTOINCREMENT,
  properties   BLOB NOT NULL,
  last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP NOT NULL );

CREATE TABLE groups (
  id           INTEGER PRIMARY KEY AUTOINCREMENT,
  name         TINYTEXT UNIQUE NOT NULL,
  last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP NOT NULL );

CREATE TABLE members (
  id_contact   INTEGER,
  id_group     INTEGER );