Calling User-Defined Function in SELECT

Question

Can I do something like:
SELECT my_func(col_1) from tab_1

Answer 1

SQL> CREATE OR REPLACE TYPE varchar2_pair_ot AS OBJECT
  2  ( var1 VARCHAR2(1000)
  3  , var2 VARCHAR2(1000) );
  4  /
Type created.
SQL> CREATE OR REPLACE FUNCTION my_func
  2      ( p_blah VARCHAR2 )
  3      RETURN varchar2_pair_ot
  4  AS
  5  BEGIN
  6      RETURN varchar2_pair_ot(LOWER(p_blah), UPPER(p_blah));
  7  END my_func;
  8  /
Function created.
SQL> CREATE TABLE blah
  2  ( b1 VARCHAR2(10)
  3  , b2 VARCHAR2(10) );
Table created.
SQL> CREATE TABLE xyz
  2  ( abc VARCHAR2(10) );
Table created.
SQL> INSERT INTO xyz VALUES ('Blah');
1 row created.
SQL> INSERT INTO blah(b1, b2)
  2  SELECT v.f.var1, v.f.var2
  3  FROM   ( SELECT my_func(abc) AS f
  4           FROM   xyz ) v;
1 row created.
SQL> SELECT * FROM blah;
B1         B2
blah       BLAH
1 row selected.