Observe the following table and answer the parts
(i) and (ii):
(i) In the above table, can we have Qty as primary key.
Answer:
Primary key refers to a set of one or more attributes which can uniquely identify tuples in a relation.
In the above table, there is a duplication of values in the column Qty. So the attribute Qty cannot uniquely identify the tuples in a relation. Hence, we cannot set Qty as the primary key.
(ii) What is the cardinality and degree of the above table?
Answer:
- Cardinality refers to the number of tuples/rows in a table.
- Degree refers to the number of attributes/columns in a table.
So for the above table,
Cardinality = 5
Degree = 4