Please explain what is the functionality of TABLE()

Question

Hi all,
My name is Suman. Engg Grad 2006 passed out and now working with Microsoft.
I am new to PL/SQL. Not aware of the exact usage of TABLE().
Could any of you kindly explain me ( if possible with an implementation).
My situation : Recently when i planned to use explain plan for a query, I happened to come across this query
select * from TABLE(DBMS_XPLN.DISPLAY('PLAN_TABLE','STATEMENT_ID);
I would be grateful if you could explain me what TABLE() does generally and what it does in the above Query.
Regards,
Suman

Answer 1

Very simplistically, it allows one to call a PL/SQL function (returning a collection), and pivot the contents of that collection into rows.
An example:
SQL> create or replace type TMyRow is object
2 (
3 object_id number,
4 object_path varchar2(4000)
5 );
6 /
Type created.
SQL>
SQL> create or replace type TMyCollection is table of TMyRow;
2 /
Type created.
SQL>
SQL>
SQL> create or replace function MyFunc( cUser varchar2 ) return TMyCollection is
2 collection TMyCollection;
3 begin
4 select
5 TMyRow( object_id, owner||'\'||object_type||'\'||object_name )
6 bulk collect into collection
7 from all_objects
8 where owner = UPPER(cUser)
9 order by
10 object_type,
11 object_name;
12
13 return( collection );
14 end;
15 /
Function created.
SQL> show errors
No errors.
SQL>
SQL> select MyFunc(USER) from dual; -- output formatted for readability
MYFUNC(USER)(OBJECT_ID, OBJECT_PATH)
TMYCOLLECTION(
TMYROW(68776, 'BILLY\FUNCTION\COUNTTYPE'),
TMYROW(92945, 'BILLY\FUNCTION\FORCECOLUMNS'),
..<snipped>..
TMYROW(61478, 'BILLY\VIEW\VTEST')
SQL> -- change the collection into a SQL type table with rows and columns
SQL> select * from TABLE( MyFunc(USER) ) where rownum < 11;
OBJECT_ID OBJECT_PATH
68776 BILLY\FUNCTION\COUNTTYPE
92945 BILLY\FUNCTION\FORCECOLUMNS
69689 BILLY\FUNCTION\FUNCTEST
63225 BILLY\FUNCTION\GETSEQUENCE
55818 BILLY\FUNCTION\HORSENAME
68782 BILLY\FUNCTION\LIST
72644 BILLY\FUNCTION\MAKESET
93331 BILLY\FUNCTION\MYFUNC
69200 BILLY\FUNCTION\PL_NVL
69476 BILLY\FUNCTION\SIEMENSDEVICETABLE
10 rows selected.
SQL>