Oracle object definitions

To get the DDL of any object in the database, DMBS_METADATA package can be used.

DBMS_METADATA.GET_DDL
(object_type IN VARCHAR2,
name IN VARCHAR2,
schema IN VARCHAR2 DEFAULT NULL,
version IN VARCHAR2 DEFAULT 'COMPATIBLE',
model IN VARCHAR2 DEFAULT 'ORACLE',
transform IN VARCHAR2 DEFAULT 'DDL')
RETURN CLOB;

Oracle Documentation

usage example:

select DBMS_METADATA.GET_DDL('VIEW','ALL_CONSTRAINTS','SYS') from dual;