Search notes:

DBMS_METADATA.GET_DDL

DBMS_METADATA.GET_DDL returns the definition of a single object as DDL statement.
This function is meant for casual browsing. For more detailed object access, the open, fetch_*, close interface should be used. 
FUNCTION 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;

begin
   dbms_metadata.set_transform_param(dbms_metadata.session_transform, 'PRETTY'            , true );
   dbms_metadata.set_transform_param(dbms_metadata.session_transform, 'CONSTRAINTS'       , true );
   dbms_metadata.set_transform_param(dbms_metadata.session_transform, 'STORAGE'           , false);
   dbms_metadata.set_transform_param(dbms_metadata.session_transform, 'SEGMENT_ATTRIBUTES', false);
end;
/

select
   dbms_metadata.get_ddl('TABLE', 'TQ84_TAB', user)
from
   dual;
When using dbms_metadata.get_ddl in SQL*Plus, the following settings should be adjusted (see also Displying CLOB values in SQL*Plus). 
set pagesize             0
set long          10000000
set longchunksize 10000000
set linesize         32767

See also

DBMS_METADATA.GET_DEPENDENT_DDL returns the meta data for objects that are dependent on a base object.
Using dbms_metadata.get_ddl to extract (existing) foreign keys.
dbms_metadata

Index

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/developm...', 1758199098, '216.73.216.150', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/development/databases/Oracle/installed/packages/dbms/metadata/api/get/ddl/index(76): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78