DML on nested tables using SQL

Question

Hello. Can anyone tell me what's wrong??
SQL> create type mytype as table of varchar2(20);
Type created
real: 78
SQL> declare
2 c mytype;
3 begin
4 select table_name bulk collect into c from user_tables;
5 delete from table(cast(c as mytype));
6 end;
7 /
declare
ERROR at line 1:
ORA-06550: line 5, column 13:
PL/SQL: ORA-00903: invalid table name
ORA-06550: line 5, column 1:
PL/SQL: SQL Statement ignored
real: 31

Answer 1

we cannot use variables in regular SQL. It has to be
dynamic, viz
begin
for r in ( select table_name from user_tables )
loop
execute immediate ' delete from '||r.table_name;
d loop;
end;
/Cheers, APCyes, but user_tables was only a example. I want to load some data into nested table using BULK COLLECT and then perform some operation on this pl/sql table.
For example:
SELECT col BULK COLLECT INTO c FROM a_table;
SELECT * BULK COLLECT INTO d FROM TABLE(CAST (c AS sql_type));
--After that c and d contain the same data
--but for example
UPDATE TABLE(CAST(c AS sql_type)) Set c.col=...;
generates invalid table name.
Why SELECT INTO works, and UPDATE doesn't (all of this was in PL/SQL context, not SQL).