text: select
  	c.custkey,
  	c.name,
  	sum(l.extendedprice * (1 - l.discount)) as revenue,
  	c.acctbal,
  	n.name,
  	c.address,
  	c.phone,
  	c.comment
  from
  	customer c,
  	orders o,
  	lineitem l,
  	nation n
  where
  	c.custkey = o.custkey
  	and l.orderkey = o.orderkey
  	and o.orderdate >= date('1993-07-01')
  	and o.orderdate < date('1993-07-01', '+1 day')
  	and l.returnflag = 'R'
  	and c.nationkey = n.nationkey
  group by
  	c.custkey,
  	c.name,
  	c.acctbal,
  	c.phone,
  	n.name,
  	c.address,
  	c.comment
  order by
  	revenue desc;