Dispite effective designs that aim to achieve good data, however, some anomolies are introduced during use of the data.

Discuss attribute semantics as an informal measure of goodness for a relational schema – that is, ways that attributes and be constructed during conception to achieve good data. Illustrate with example
Discuss Insertion, Deletion, and modification anomolies. Why are they considered bad? Illustrate with examples.
Why should NULLs in a relation be avoided as much as possible? Discuss the problem of spurious tuples and how to prevent it.