PLS-00355 error whike creating a new table type - oracle

Question

I'm getting the PLS-00355 error while trying to create the new type like this:
CREATE OR REPLACE TYPE DAYS_T IS TABLE OF VARCHAR(250) INDEX BY BINARY_INTEGER;
Any clue what is wrong?
Many thanks!

Answer 1

This is what you did and how Oracle responded:
SQL> CREATE OR REPLACE TYPE DAYS_T IS TABLE OF VARCHAR(250) INDEX BY BINARY_INTEGER;
2 /
Warning: Type created with compilation errors.
SQL> show err
Errors for TYPE DAYS_T:
LINE/COL ERROR
-------- -----------------------------------------------------------------
0/0 PL/SQL: Compilation unit analysis terminated
1/16 PLS-00355: use of pl/sql table not allowed in this context
On the other hand:
SQL> CREATE OR REPLACE TYPE DAYS_T IS TABLE OF VARCHAR2(250);
2 /
Type created.
SQL>
Responding to your comment: if you declared type at PL/SQL level (not SQL), then your code (without create or replace, though) would be OK (line #2 is what you used, literally):
SQL> declare
2 TYPE DAYS_T IS TABLE OF VARCHAR(250) INDEX BY BINARY_INTEGER;
3 begin
4 null;
5 end;
6 /
PL/SQL procedure successfully completed.
SQL>

Answer 2

You can define a nested table collection type in the SQL scope using:
CREATE OR REPLACE TYPE DAYS_T IS TABLE OF VARCHAR(250);
You can define an associative array collection type in a PL/SQL scope using:
DECLARE
TYPE DAYS_T IS TABLE OF VARCHAR(250) INDEX BY BINARY_INTEGER;
BEGIN
NULL;
END;
/
You could also locally define a nested-table collection type in a PL/SQL scope using:
DECLARE
TYPE DAYS_T IS TABLE OF VARCHAR(250);
BEGIN
NULL;
END;
/
However, you cannot define an associative array collection type in the SQL scope as it is a PL/SQL only data type.
You then asked in comments:
But how can I add an index?
They both have an index.
For example, after declaring the type in SQL, you can use the nested table collection in PL/SQL like this:
DECLARE
v_days DAYS_T;
BEGIN
v_days := DAYS_T(); -- Initialise the collection.
v_days.EXTEND(3); -- Extend the collection by 3 elements.
v_days(1) := 'Monday'; -- Set the first element.
v_days(3) := 'Wednesday'; -- Set the third element.
FOR i IN 1 .. v_days.COUNT LOOP
DBMS_OUTPUT.PUT_LINE( i || ' = ' || v_days(i) );
END LOOP;
END;
/
Which outputs:
1 = Monday
2 =
3 = Wednesday
db<>fiddle here