Query to group dept codes in a row

Question

Hi Gurus,
I am trying to write a sql to list all the employees and their dept codes in duration of 5 years.
I have a table like
Emp Dept_codes
1 10,20,40
1 30,50
2 10,40
2 30
3 70
EMp and Dept_codes are character types.
Is it possible to have a solution like
Emp Dept_codes
1 10,20,30,40,50
2 10,30,40
3 70
Please let me know if this is possible using a SQL stmt.
Thanks in advance.

Answer 1

The question is not about the data modelIt's all about the data model, you wouldn't have such difficulties if the data model would be normalized.
Anyway, try this, it is a combination of algorithms described here and here
SQL> SELECT emp,
  2         LTRIM(MAX(SYS_CONNECT_BY_PATH(dept_code,','))
  3         KEEP (DENSE_RANK LAST ORDER BY curr),',') AS dept_codes
  4  FROM   (SELECT emp,
  5                 dept_code,
  6                 ROW_NUMBER() OVER (PARTITION BY emp ORDER BY dept_code) AS curr,
  7                 ROW_NUMBER() OVER (PARTITION BY emp ORDER BY dept_code) -1 AS prev
  8          FROM   (SELECT emp,
  9                         EXTRACTVALUE(xt.column_value,'e') dept_code
10                  FROM   t,
11                         TABLE(XMLSEQUENCE
12                               ( EXTRACT
13                                 ( XMLTYPE('<coll><e>' || REPLACE(dept_codes,',','</e><e>') || '</e></coll>')
14                                 , '/coll/*')
15                              )) xt
16                 )
17         )
18  GROUP BY emp
19  CONNECT BY prev = PRIOR curr AND emp = PRIOR emp
20  START WITH curr = 1;
       EMP DEPT_CODES
         1 10,20,30,40,50
         2 10,30,40
         3 70
SQL>