We can determine the last time a user table was altered 
using the below query.

SELECT name, create_date, modify_date
FROM sys.tables
ORDER BY modify_date DESC

The modify_date column is updated whenever a column is 
added or altered for the table. 
It is also updated if the clustered index is changed.

select table_name from user_tables where last_analyzed in
(select max(last_analyzed) from user_tables)

select table_name, to_char(last_analyzed, 'DD-MM-YY
HH:MI:SS') from user_tables where last_analyzed in (select
max(last_analyzed) from user_tables)