Plsql Collections help

Question

Database table has two columns category and products.
Table: catalog
category products
fruit apple
vegetable carrot
soda pepsi
vegetable potato
fruit grapes
fruit orange
vegetable cabbage
soda coke
i need to read the records from table catalog and store them in some sort of plsql collection. I then have to read from that collection and write output as follows:
Note: the categories and products should be sorted alphabetically in output.
OUTPUT
fruit apple, grapes, orange
soda coke, pepsi
vegetable cabbage, carrot, potato
please help me as how this can be done?
Thanks
G

Answer 1

Without collections:
SQL> DECLARE
  2      CURSOR c
  3        IS
  4          WITH t AS (
  5                     SELECT 'fruit' category,'apple' product FROM dual UNION ALL
  6                     SELECT 'vegetable','carrot' FROM dual UNION ALL
  7                     SELECT 'soda','pepsi' FROM dual UNION ALL
  8                     SELECT 'vegetable','potato' FROM dual UNION ALL
  9                     SELECT 'fruit','grapes' FROM dual UNION ALL
10                     SELECT 'fruit','orange' FROM dual UNION ALL
11                     SELECT 'vegetable','cabbage' FROM dual UNION ALL
12                     SELECT 'soda','coke' FROM dual
13                    )
14          SELECT  category,
15                  ltrim(sys_connect_by_path(product,', '),', ') product_list
16            FROM  (
17                   SELECT  category,
18                           product,
19                           row_number() over(partition by category order by product) rn
20                     FROM  t
21                  )
22            WHERE connect_by_isleaf = 1
23            START WITH rn = 1
24            CONNECT BY category = PRIOR category
25                   AND rn = PRIOR rn + 1
26            ORDER BY category;
27  BEGIN
28      FOR v_rec IN c LOOP
29        DBMS_OUTPUT.PUT_LINE(rpad(v_rec.category,10) || v_rec.product_list);
30      END LOOP;
31  END;
32  /
fruit     apple, grapes, orange
soda      coke, pepsi
vegetable cabbage, carrot, potato
PL/SQL procedure successfully completed.
SQL> And in plain SQL:
SQL> COLUMN PRODUCT_LIST FORMAT A50
SQL> WITH t AS (
  2             SELECT 'fruit' category,'apple' product FROM dual UNION ALL
  3             SELECT 'vegetable','carrot' FROM dual UNION ALL
  4             SELECT 'soda','pepsi' FROM dual UNION ALL
  5             SELECT 'vegetable','potato' FROM dual UNION ALL
  6             SELECT 'fruit','grapes' FROM dual UNION ALL
  7             SELECT 'fruit','orange' FROM dual UNION ALL
  8             SELECT 'vegetable','cabbage' FROM dual UNION ALL
  9             SELECT 'soda','coke' FROM dual
10            )
11  SELECT  category,
12          ltrim(sys_connect_by_path(product,', '),', ') product_list
13    FROM  (
14           SELECT  category,
15                   product,
16                   row_number() over(partition by category order by product) rn
17             FROM  t
18          )
19    WHERE connect_by_isleaf = 1
20    START WITH rn = 1
21    CONNECT BY category = PRIOR category
22           AND rn = PRIOR rn + 1
23    ORDER BY category
24  /
CATEGORY  PRODUCT_LIST
fruit     apple, grapes, orange
soda      coke, pepsi
vegetable cabbage, carrot, potato
SQL> SY.