You can use the analytic form of the count
function
SQL> ed
Wrote file afiedt.buf
1 with data_row as (
2 select 1 as colA from dual union all
3 select 2 as cola from dual union all
4 select 3 as cola from dual
5 )
6 select colA, rownum, count(*) over () cnt
7* from data_row
SQL> /
COLA ROWNUM CNT
---------- ---------- ----------
1 1 3
2 2 3
3 3 3