In Sql database table how to retrieve the latest data entered? what is the code for that?

If you have an ID field, just get the record with the highest ID. Something like:
SELECT * FROM table WHERE Id = (SELECT Max(Id) FROM table)

You could also just do SELECT * FROM table ORDER BY Id DESC, and get a set with the newest record first. In the programming language you're using to execute the SQL commands, you could then just access the first record in the set.