Run this script first and you will get the script called disable.sql
when you disable the constraint and finish your job and edit the script disable.sql change disable to enable and run it again and all disabled constraints will be enabled again.

set feed off pages 0 head off echo off line 100 ver off
col col1 newline

accept username prompt 'Please enter owner of Tables: '

REM #
REM # create script to disable all referencial constraints
REM #
spool disable.sql
select 'alter table '|| r_owner ||'.'||
table_name ||' disable constraint '||
constraint_name ||';'
from user_constraints
where r_owner = upper('&username')
and constraint_type = 'R';
spool off