Error while creating a custom type

Question

i'am having the following statement,
create or replace type myType as object ( x varchar2(20) not null )
when i try to create, i get the following error,
PLS-00218: a variable declared NOT NULL must have an initialization assignment
now how do i create an object whose value(S) should be not null...???...............

Answer 1

my_type.id here is nonsense. It's NOT a type at all.
OUT and IN OUT parameters can't be assigned with DEFAULT value:
SQL> create procedure wrong_params(id in out number default 0)
  2  is
  3  begin
  4   null;
  5  end;
  6  /
Warning: Procedure created with compilation errors.
SQL> show error
Errors for PROCEDURE WRONG_PARAMS:
LINE/COL ERROR
1/24     PLS-00230: OUT and IN OUT formal parameters may not have default
         expressionsIf you declare variable as NOT NULL you have to assign default value to prevent
PL/SQL compiler confusion:
SQL> declare
  2   id number not null;
  3  begin
  4   null;
  5  end;
  6  /
id number not null;
ERROR at line 2:
ORA-06550: line 2, column 5:
PLS-00218: a variable declared NOT NULL must have an initialization assignment
SQL> declare
  2   id number not null default 10;
  3  begin
  4   null;
  5  end;
  6  /
PL/SQL procedure successfully completed.
I read out parameters cannot be of type not nullFormal arguments of procedures/functions can not be declared as NOT NULL
anyway they are OUT or IN.
But actual parameters (variables you are passing into procedures) can be declared
as not null. Because of this this call cause the error - procedure passes null value ( [i]default value for OUT formal argument ) out to actual parameter which is not null:
SQL> create or replace procedure my_proc
  2  (formal_argument out number)
  3  is
  4  begin
  5   null;
  6  end;
  7  /
Procedure created.
SQL> declare
  2   actual_argument number not null := 0;
  3  begin
  4    my_proc(actual_argument);
  5  end;
  6  /
declare
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error
ORA-06512: at line 4See Tom Kyte's threads for more explanations:
http://asktom.oracle.com/pls/ask/f?p=4950:8:12505620454267529210::NO::F4950_P8_DISPLAYID,F4950_P8_CRITERIA:325417134618
Rgds.