Question

Cardinality of a table T1 is 10 and of table, T2 is 8 and the two relations are union compatible.

1. What will be the maximum possible cardinality of T1 ∪ T2? 

2. What will be the minimum possible cardinality of T1 ∩ T2?

Answer 1

1. Degree(CD) - the number of Columns is the Degree 

Cardinality (RC)-: the number of Rows is the Cardinality 

T1 ∪ T2 = Sum of cardinalities of Table 1 and Table 2 

i.e. T1 ∪ T2 = 10 + 8 = 18.

2. T1 ∩ T2 is the common rows(tuples) in T1 and T2 If there is no common tuples then T1 n T2 is 0 hence the cardinality is 0.