text: select
    c_custkey,
    o_orderkey,
    a.cnt
  
  from (
  
    select
      c_custkey,
      count(*) as cnt
  
    from
      customer
  
    group by
      c_custkey
  
  ) a left outer join (
  
    select
      o_orderkey,
      count(*) as cnt
  
    from
      orders
  
    where
      o_orderkey is not null
  
    group by
      o_orderkey
  
  ) b on (a.c_custkey = b.o_orderkey);