sql>create or replace procedure getDDL
  2    (p_table_name in user_tables.table_name%type,
  3     p_ddl        out clob)
  4  is
  5  begin
  6    p_ddl := dbms_metadata.get_ddl('TABLE', p_table_name);
  7  end;
  8  /

Procedure created.

sql>var ddl clob
sql>set long 200
sql>exec getDDL('EMP', :ddl)

PL/SQL procedure successfully completed.

sql>print ddl

DDL
------------------------------------------------------------------------------

  CREATE TABLE "BARRYT"."EMP" 
   (    "EMPNO" NUMBER(4,0) NOT NULL ENABLE, 
        "E
NAME" VARCHAR2(10), 
        "JOB" VARCHAR2(9), 
        "MGR" NUMBER(4,0), 
        "HIREDATE" DAT
E, 
        "SAL" NUMBER(7,2), 
        "COMM" NUMBER(7,2)

SQL> col data_type format a20
SQL> col column_name format a20
SQL> SELECT column_name
  2       , data_type
  3       , data_length
  4       , data_precision
  5       , data_scale
  6    FROM user_tab_columns
  7   WHERE table_name = 'DEPARTMENTS'
  8  /

COLUMN_NAME          DATA_TYPE            DATA_LENGTH DATA_PRECISION DATA_SCALE
-------------------- -------------------- ----------- -------------- ----------
DEPARTMENT_ID        NUMBER                        22              4          0
DEPARTMENT_NAME      VARCHAR2                      30
MANAGER_ID           NUMBER                        22              6          0
LOCATION_ID          NUMBER                        22              4          0

SQL> desc departments
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 DEPARTMENT_ID                             NOT NULL NUMBER(4)
 DEPARTMENT_NAME                           NOT NULL VARCHAR2(30)
 MANAGER_ID                                         NUMBER(6)
 LOCATION_ID                                        NUMBER(4)

SQL> select * from table_name;
select * from table_name
              *
ERROR at line 1:
ORA-00942: table or view does not exist

SQL> CREATE PROCEDURE foo(p_tab_name IN VARCHAR2)
  2  IS
  3    CURSOR c_cols(c_tname VARCHAR2)
  4        IS
  5    SELECT column_name
  6         , data_type
  7         , data_length
  8         , data_precision
  9         , data_scale
 10      FROM user_tab_columns
 11     WHERE table_name = c_tname;
 12  BEGIN
 13    FOR the_column IN c_cols(p_tab_name)
 14    LOOP
 15      -- do your processing here
 16      dbms_output.put_line(the_column.column_name||' is a '
 17                         ||the_column.data_type||' COLUMN.');
 18    END LOOP;
 19  END;
 20  /

Procedure created.

SQL> set serverout on
SQL> exec foo('EMPLOYEES')
EMPLOYEE_ID is a NUMBER COLUMN.
FIRST_NAME is a VARCHAR2 COLUMN.
LAST_NAME is a VARCHAR2 COLUMN.
EMAIL is a VARCHAR2 COLUMN.
PHONE_NUMBER is a VARCHAR2 COLUMN.
HIRE_DATE is a DATE COLUMN.
JOB_ID is a VARCHAR2 COLUMN.
SALARY is a NUMBER COLUMN.
COMMISSION_PCT is a NUMBER COLUMN.
MANAGER_ID is a NUMBER COLUMN.
DEPARTMENT_ID is a NUMBER COLUMN.

PL/SQL procedure successfully completed.

SQL> exec foo('JOBS')
JOB_ID is a VARCHAR2 COLUMN.
JOB_TITLE is a VARCHAR2 COLUMN.
MIN_SALARY is a NUMBER COLUMN.
MAX_SALARY is a NUMBER COLUMN.

PL/SQL procedure successfully completed.

SQL>