Can one use dynamic SQL statements from PL/SQL?
Starting from Oracle8i one can use the "EXECUTE IMMEDIATE" statement to execute dynamic SQL and PL/SQL statements (statements created at run-time). Look at these examples. Note that statements are NOT terminated by semicolons:  
 EXECUTE IMMEDIATE 'CREATE TABLE x (a NUMBER)';
 
 -- Using bind variables...
 sql_stmt := 'INSERT INTO dept VALUES (:1, :2, :3)';
 EXECUTE IMMEDIATE sql_stmt USING dept_id, dept_name, location;
 
        -- Returning a cursor...
 sql_stmt := 'SELECT * FROM emp WHERE empno = :id';
 EXECUTE IMMEDIATE sql_stmt INTO emp_rec USING emp_id;
 
One can also use the older DBMS_SQL package (V2.1 and above) to execute dynamic statements. Look at these examples:  
 CREATE OR REPLACE PROCEDURE DYNSQL AS
   cur integer;
   rc  integer;
 BEGIN
   cur := DBMS_SQL.OPEN_CURSOR;
   DBMS_SQL.PARSE(cur, 'CREATE TABLE X (Y DATE)', DBMS_SQL.NATIVE);
   rc := DBMS_SQL.EXECUTE(cur);
   DBMS_SQL.CLOSE_CURSOR(cur);
 END;
 /
 
More complex DBMS_SQL example using bind variables:  
 CREATE OR REPLACE PROCEDURE DEPARTMENTS(NO IN DEPT.DEPTNO%TYPE) AS
   v_cursor integer;
   v_dname  char(20);
   v_rows   integer;
 BEGIN
   v_cursor := DBMS_SQL.OPEN_CURSOR;
   DBMS_SQL.PARSE(v_cursor, 'select dname from dept where deptno > :x', DBMS_SQL.V7);
   DBMS_SQL.BIND_VARIABLE(v_cursor, ':x', no);
   DBMS_SQL.DEFINE_COLUMN_CHAR(v_cursor, 1, v_dname, 20);
   v_rows := DBMS_SQL.EXECUTE(v_cursor);
   loop
     if DBMS_SQL.FETCH_ROWS(v_cursor) = 0 then
        exit;
     end if;
     DBMS_SQL.COLUMN_VALUE_CHAR(v_cursor, 1, v_dname);
     DBMS_OUTPUT.PUT_LINE('Deptartment name: '||v_dname);
   end loop;
   DBMS_SQL.CLOSE_CURSOR(v_cursor);
 EXCEPTION
   when others then
        DBMS_SQL.CLOSE_CURSOR(v_cursor);
        raise_application_error(-20000, 'Unknown Exception Raised: '||sqlcode||' '||sqlerrm);
 END;
 /