Functions cannot be invoked from Select Query

Functions cannot be invoked from Select Query : if the function is having any ddl/dml operations inside it.

Example :

create or replace function xx_temp_fun(p_deptno number)

return char

is

begin

insert into xx_dept(deptno,dname) values (p_deptno,'Bench') ;

commit;

return 'x';

end ;

select xx_temp_fun(21) from dual; --> this will give you an error. as the function written above is having DML operations inside it.

The follow works without any error.

declare

v_char varchar2(10);

begin

v_char := xx_temp_fun(19);

end;