text: -- examples on date functions
  
  -- current date and time
  select current_date;
  select current_timestamp, now();
  select localtimestamp, current_timestamp::timestamp;
  select current_time, localtime;
  select current_timestamp, localtimestamp;
  
  -- operators -, +
  select current_date - 1 as yesterday, current_date + 1 as tomorrow;
  
  select extract(year from now()), extract(month from now()), extract(dow from now()), extract(doy from now());
  