Last date from a group in oracle table

Asked to run a query against a two column table, one column having a procedure name and the other with the date the procedure was last ran.

e.g.

PROC_NAME                      START_DTM
------------------------------ ---------
TVM Cash Balance               05-NOV-20
TVM Cash Balance               12-NOV-20
TVM Cash Balance               02-DEC-20
TVM Cash Balance               01-DEC-20
TVM Cash Balance               03-DEC-20
TVM Cash Balance               04-DEC-20
TVM Cash Balance               30-SEP-20
TVM Cash Balance               18-SEP-20
TVM Cash Balance               01-SEP-20
TVM Cash Balance               29-SEP-20
TVM Cash Balance               12-SEP-20

We needed to select the last date for each procedure.

This works :

select proc_name, max(start_dtm) from dw_main.proc_run_log where proc_name in (select distinct(proc_name) from dw_main.proc_run_log) group by proc_name order by proc_name;

PROC_NAME                                         MAX(START

------------------------------                            ---------

Summarize Tap RW Error Summary     04-DEC-20

Summarize Tap Speed Summary          04-DEC-20
Summarize Txn Timing                          04-DEC-20
TVM Cash Balance                                04-DEC-20
Update Card Statuses                           04-DEC-20

....

131 rows selected.

We wanted to double check (and to show how this could also be achieved in pl/sql) to be absolutely certain so put this together (the sql is also easier to understand ):

create or replace procedure ruslist
    is
    proc_rus varchar2(30);
    start_rus date;
CURSOR d1 IS SELECT distinct proc_name from dw_main.proc_run_log order by proc_name;
CURSOR d2 IS SELECT  max(start_dtm) from  dw_main.proc_run_log where proc_name = proc_rus;
BEGIN
    open d1;
    LOOP
    FETCH d1 into proc_rus;
  EXIT when d1% NOTFOUND;
    dbms_output.put( proc_rus);
   open d2;
   LOOP
    FETCH d2 into start_rus;
   EXIT when d2% NOTFOUND;
    dbms_output.put_line('      '||start_rus);
  END LOOP;
CLOSE d2;
  END LOOP;
CLOSE d1;
EXCEPTION
   WHEN OTHERS THEN
      raise_application_error(-20001,'An error was encountered - '||SQLCODE||' -ERROR- '||SQLERRM);
END ruslist;

......

Summarize Tap RW Error Summary       04-DEC-20
Summarize Tap Speed Summary            04-DEC-20
Summarize Txn Timing                            04-DEC-20
TVM Cash Balance                                  04-DEC-20
Update Card Statuses                              04-DEC-20

PL/SQL procedure successfully completed.

SQL>

Happy days.