Problem in functions

Question

how to write ddl statements in function. give me with example
how to to dml statements in function.give me sample code.
i am calling one function in sql experession.
that function constainf the dml statemsts. how to write that function.

Answer 1

First of all in theory you can't run DDL in PL/SQL and can't run DML from within a function called from SQL. But...
... there's a workaround using execute immediate and using pragma autonomous transaction, which is full of drawbacks and reasons why you shouldn't do it.
One has to be fully aware of its consequences before using this pragma which is probably the single most misused feature in Oracle (a close call with execute immediate).
You said you want to run that function containing DML or DDL from an SQL? I can't help but think you shouldn't be doing that.
What exactly do you need to accomplish that lead you to this solution?
If you explain it I'm sure someone will come up with a better solution hands down.
SQL> create or replace function big_no_no return varchar2 authid current_user as
  2  begin
  3    execute immediate 'create table t1(col1 number)';
  4    return 'THIS IS WRONG';
  5  end;
  6  /
Function created
SQL> select big_no_no from dual;
select big_no_no from dual
ORA-14552: cannot perform a DDL, commit or rollback inside a query or DML
ORA-06512: at "FSITJA.BIG_NO_NO", line 3There's a reason why they created the error code ORA-14552, and that's to save people from shooting themselves in the foot.
Of course it's easy to bypass but you should acknowledge it's not without side effects.
SQL> create or replace function big_no_no return varchar2 authid current_user as
  2  pragma autonomous_transaction;
  3  begin
  4    execute immediate 'create table t1(col1 number)';
  5    return 'THIS IS WRONG';
  6  end;
  7  /
Function created
SQL> select * from t1;
select * from t1
ORA-00942: table or view does not exist
SQL> select big_no_no from dual;
BIG_NO_NO
THIS IS WRONG
SQL> select * from t1;
      COL1
SQL>