Question

1. Discuss attribute semantics as an informal measure of goodness for a rela- tion schema.

Answer 1

Answer:

When  attributes are intertwined together they form a relationship, it is believed   that attributes that have one  to one relation have a proper interpretation and better meaning which are assumed to be associated by them .

Tables that does not have a complete  data may encounter  problems called update anomalies, which have different categories  like  insertion, deletion, or modification anomalies

Explanation:

• When  attributes are intertwined together they form a relationship, it is believed   that attributes that have one  to one relation have a proper interpretation and better meaning which are assumed to be associated by them . The semantics of a relation is defined as the  the exposition of value    attribute  in a tuple. That is to say a better way of the explanation  of a relations attributes  is a measure of informal well known relation designed.

• Tables that does not have a complete  data may encounter  problems called update anomalies, which have different categories  like  insertion, deletion, or modification anomalies. For  example of a table with on useful  data data called EMP-Department. There are two categories  of insertion anomalies,  For this method to be useful  for the detail  of a new employee in Emp-Department, we must add either value attribute   for the department that the employee is engaged in  or void. For the second method , an  the attribute value must be entered for the department 2 well so that there will be a  consistent value for department number 5 in other field in  EMP-Department. When a department does not have a new employee It is difficult to insert the department value

Answer 2

Answer:

1. The attribute semantics as an informal measure of goodness for a relation schema can be of two types, (i) Logical (or conceptual) level—It tells about how the users interpret the relation schemas and the meaning of their attributes. (ii) Implementation (or storage) level—It tells about how tuples and their values are stored in storage.

2. Insertion anomalies means inserting a new attribute in the existing database, deletion means deleting any particular attribute and modification means modifying the data, these are considered bad because, when this process applies to any database we have to select the correct path and location of data otherwise it will not work correctly, and make a copied file.