to search and replace the string in all db objects source code in oracle database
select name,text from user_source where text like '%DZONE';

select regexp_replace (dbms_metadata.get_ddl (object_type, object_name, USER),'DZONE','SZONE')
from (
select distinct object_name, object_type
 from user_procedures where object_name in (select name from user_source where text like '%DZONE%')
)

Update user_source
Set text = 'SZONE'
Where text like '%DZONE';