How to Generate DDL Statements for an Object in Oracle.

Use dbms_metadata.get_ddl package to Generate DDL Statements for a different type of Objects in Oracle Database usage as below: 

select dbms_metadata.get_ddl('OBJECT_TYPE','OBJECT_NAME','OWNER') from dual; -If you are executing as SYS or SYSTEM

OR

select dbms_metadata.get_ddl('OBJECT_TYPE','OBJECT_NAME') from dual; -If you are already connected with Schema

Examples: 

# Generate DDL for all Objects of Schema.

SQL> set feedback off

SQL> set echo off 

SQL> set heading 999

SQL> set lines 100 

SQL> set long 90000

SQL> select dbms_metadata.GET_DDL(u.object_type,u.object_name,'SCOTT') from dba_objects u where owner = 'SCOTT';

# Generate DDL for Specific Object of Schema.

SQL> set feedback off

SQL> set echo off

SQL> set heading 999

SQL> set lines 100 

SQL> set long 90000

SQL> spool DDL_SCOTT_EMP.lst;

SQL> select dbms_metadata.get_ddl('TABLE','EMP','SCOTT') from dual;

DBMS_METADATA.GET_DDL('TABLE','EMP')

--------------------------------------------------------------------------------

  CREATE TABLE "SCOTT"."EMP"

   ( "EMPNO" NUMBER(4,0),

"ENAME" VARCHAR2(10),

"JOB" VARCHAR2(9),

"MGR" NUMBER(4,0),

"HIREDATE" DATE,

"SAL" NUMBER(7,2),

"COMM" NUMBER(7,2),

"DEPTNO" NUMBER(2,0),

CONSTRAINT "PK_EMP" PRIMARY KEY ("EMPNO")

  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS

  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645

  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DE

FAULT CELL_FLASH_CACHE DEFAULT)

  TABLESPACE "USERS"  ENABLE,

CONSTRAINT "FK_DEPTNO" FOREIGN KEY ("DEPTNO")

 REFERENCES "SCOTT"."DEPT" ("DEPTNO") ENABLE

   ) SEGMENT CREATION IMMEDIATE

  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING

  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645

  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DE

FAULT CELL_FLASH_CACHE DEFAULT)

  TABLESPACE "USERS"

SQL> spool off;