Ordering the strings while concatenating in oracle

Question

I am using the collect function to concatenate strings for a sql query.

    select id,
    tab_to_string(CAST(COLLECT(a.level||\' \'||d.Number||\':  
    \'||to_c         


        

Answer 1

to get an ordered list, there's a few ways. the simplest is :

select id, str
  from (select id, 
               wm_concat('level : ' || to_char(nvl(eventDate,SYSDATE - 365 * 100))) 
                 over (partition by id order by eventdate) str,
               row_number() over (partition by id order by eventdate desc) rn
         from Mytable)
 where rn = 1;

or if you're using the "stragg" user defined aggregate:

  select id, str
  from (select id, 
               string_agg('level : ' || to_char(nvl(eventDate,SYSDATE - 365 * 100))) 
                 over (partition by id order by eventdate) str,
               row_number() over (partition by id order by eventdate desc) rn
         from Mytable)
 where rn = 1;

eg

SQL> select id, str
  2    from (select id,
  3                 string_agg('level : ' || to_char(nvl(eventDate,SYSDATE - 365 * 100)))
  4                   over (partition by id order by eventdate) str,
  5                 row_number() over (partition by id order by eventdate desc) rn
  6           from Mytable)
  7   where rn = 1;

        ID STR
---------- ----------------------------------------------------------------------
         1 level : 27-MAR-08,level : 27-JAN-09,level : 02-APR-10
         2 level : 07-JUN-06,level : 02-NOV-08,level : 27-DEC-08
         3 level : 27-MAR-06,level : 02-APR-10,level : 27-JUL-10