@AccessControl.authorizationCheck: #NOT_REQUIRED
@EndUserText.label: 'Air quality per station'
define view entity {{P}}I_AIR_QUALITY
  as select from {{p}}station as sta
    inner join   {{p}}reading as rea on rea.station_id = sta.station_id
{
  key sta.station_id                            as station_id,
      sta.station_name                          as station_name,
      count( * )                                as reading_count,
      avg( rea.pm_value as abap.dec( 5, 1 ) )   as avg_pm,
      max( rea.pm_value )                       as max_pm,
      case when max( rea.pm_value ) > sta.limit_pm
                then 'HIGH'
           when max( rea.pm_value ) > sta.limit_pm * 80 / 100
                then 'MEDIUM'
           else 'LOW'
      end                                       as rating,
      abs( max( rea.pm_value ) - sta.limit_pm ) as deviation
}
group by
  sta.station_id,
  sta.station_name,
  sta.limit_pm