Notas.... você não deve ter dados redundantes (primeiro nome, sobrenome) nesta tabela, você deve ter uma tabela separada apenas para isso. Parece que suas horas estão truncadas e não arredondadas? (o arredondamento daria 1,26 na primeira linha).
with
test_data ( seq, the_date, scanid, locatn, user_id, first_name, last_name ) as (
select 103939758, to_date('05-NOV-16 14:36:22', 'dd-MON-yy hh24:mi:ss'), 194972, 'DOOR 19', 'AX9868', 'Mike', 'Derry' from dual union all
select 103939780, to_date('05-NOV-16 14:38:07', 'dd-MON-yy hh24:mi:ss'), 194972, 'DOOR 19', 'AX9868', 'Mike', 'Derry' from dual union all
select 103939792, to_date('05-NOV-16 14:39:24', 'dd-MON-yy hh24:mi:ss'), 194972, 'DOOR 19', 'AX9868', 'Mike', 'Derry' from dual union all
select 103940184, to_date('05-NOV-16 15:16:53', 'dd-MON-yy hh24:mi:ss'), 194972, 'DOOR 19', 'AX9868', 'Mike', 'Derry' from dual union all
select 103940185, to_date('05-NOV-16 15:51:41', 'dd-MON-yy hh24:mi:ss'), 194972, 'DOOR 19', 'AX9868', 'Mike', 'Derry' from dual union all
select 103940214, to_date('05-NOV-16 09:51:42', 'dd-MON-yy hh24:mi:ss'), 194993, 'DOOR 16', 'BC1910', 'Tony', 'McCann' from dual union all
select 103940215, to_date('05-NOV-16 15:19:06', 'dd-MON-yy hh24:mi:ss'), 194993, 'DOOR 16', 'BC1910', 'Tony', 'McCann' from dual
)
-- end of test data; solution (SQL query) begins below this line
select trunc(the_date) as the_date, user_id, first_name, last_name,
trunc(24 * (max(the_date) - min(the_date)), 2) as total_hrs
from test_data
group by trunc(the_date), user_id, first_name, last_name
;
THE_DATE USER_ID FIRST_NAME LAST_NAME TOTAL_HRS
--------- ------- ---------- --------- ----------
05-NOV-16 AX9868 Mike Derry 1.25
05-NOV-16 BC1910 Tony McCann 5.45
