Add a database with Supabase

create table public.notes (
  id bigint generated always as identity primary key,
  message text not null check (char_length(message) between 1 and 280),
  created_at timestamptz not null default now()
);

-- Let the website read and add notes. Nothing else.
grant select, insert on public.notes to anon;

-- Row Level Security: block everything, then allow only what the policies say.
alter table public.notes enable row level security;

create policy "Anyone can read notes"
  on public.notes for select to anon
  using (true);

create policy "Anyone can add a note"
  on public.notes for insert to anon
  with check (true);

Success. No rows returned. That is good news: the script creates things rather than reading rows, so there is nothing to show.

I followed a Supabase guide that created this table and its security rules: [paste the SQL script from this step] Rewrite it for my app instead. My idea: [your one-sentence idea]. Keep the same pattern: explicit grants to anon only for what visitors truly need, row level security enabled, and one policy per action. Explain each policy in one plain sentence.