dbdiagram

Table users as U {
  username varchar [pk]
  hashed_password varchar [not null]
  full_name varchar [not null]
  email varchar [unique, not null]
  password_changed_at timestamptz [not null, default: '0001-01-01 00:00:00Z']
  created_at timestamptz [not null, default: `now()`]
}

Table accounts as A {
  id bigserial [pk]
  owner varchar [not null, ref: > U.username]
  balance bigint [not null]
  currency varchar [not null]
  created_at timestamptz [not null, default: `now()`]
  Indexes{
    owner
    (owner, currency) [unique]
  }
}

Table entries {
  id bigserial [pk]
  account_id bigint [ref: > A.id, not null]
  amount bigint [not null, note: 'can be negative or positive']
  created_at timestamptz [not null, default: `now()`]
  Indexes{
    account_id
  }
}


Table transfers{
  id bigserial [pk]
  from_account_id bigint [ref: > A.id, not null]
  to_account_id bigint [ref: > A.id, not null]
  amount bigint [not null, note: 'must be positive']
  created_at timestamptz [not null, default: `now()`]
  Indexes{
    from_account_id
    to_account_id
    (from_account_id, to_account_id)
  }
}