You Wang thinks this is interesting: Continuing from the previous section, the literature also describes two levels of mappings that connect the three schemas From Chapter 2: The Database System Environment from Database Systems by Shripad V. Godbole, Elvis C. Foster Publisher: Apress Released: December 2014 Note this is like translation Share this highlight http://www.safaribooksonline.com/a/database-systems/5893233/ Twitter Facebook Google Plus Email Get Instant Access Now Start a Free Trial Learn about Safari for Business Have an account? Sign in. Minimise Unlock the rest of Database Systems and 30,000 other books and videos By clicking this box, you confirm that you have read and agree to the terms and conditions of our Membership Agreement, and you understand that when your trial period ends, you will be required to provide billing information if you wish to continue using the service. Unlock the rest of this book Start a Free 10-Day Trial loading Learn about Safari for Business Have an account? Sign in.