# File lib/heroku/pgutils.rb, line 16
  def resolve_db_id(input, opts={})
    name = input || opts[:default]

    # try to find addon config var name from all config vars
    # if name is 'DATABASE_URL', try to return the addon config var name for better accounting
    output = nil
    addon_config_vars = pg_config_var_names - ["DATABASE_URL"]
    addon_config_vars.each do |n|
      next unless config_vars[n] == config_vars[name]
      return n, config_vars[n], config_vars[n] == config_vars["DATABASE_URL"]
    end

    # database url isn't an alias for another var
    return name, config_vars[name], true if name == "DATABASE_URL"

    if name
      display " !   Database #{name} not found in config."
    else
      display opts[:usage_message] || " !   Specify a database with --db <DATABASE>."
    end
    display " !   "
    display " !   Available database URLs:"
    addon_config_vars.each do |v|
      str = " !   #{v}"
      str += " (currently DATABASE_URL)" if config_vars[v] == config_vars["DATABASE_URL"]
      display str
    end
    abort
  end