CREATE TABLE kunde (
  id INTEGER PRIMARY KEY, name TEXT NOT NULL, mail TEXT NOT NULL UNIQUE, angelegt_am TEXT NOT NULL DEFAULT (date('now')));
CREATE TABLE artikel (
  id INTEGER PRIMARY KEY, name TEXT NOT NULL, preis_cent INTEGER NOT NULL CHECK (preis_cent >= 0));
CREATE TABLE bestellung (
  id INTEGER PRIMARY KEY, kunde_id INTEGER NOT NULL REFERENCES kunde(id) ON DELETE RESTRICT, datum TEXT NOT NULL);
CREATE TABLE bestellposition (
  bestellung_id INTEGER NOT NULL REFERENCES bestellung(id) ON DELETE CASCADE,
  artikel_id INTEGER NOT NULL REFERENCES artikel(id) ON DELETE RESTRICT,
  menge INTEGER NOT NULL CHECK (menge > 0), preis_cent INTEGER NOT NULL,
  PRIMARY KEY (bestellung_id, artikel_id));
CREATE INDEX idx_bestellung_kunde ON bestellung(kunde_id);
CREATE INDEX idx_position_artikel ON bestellposition(artikel_id);