Database Systems

The relations of two sub-entity sets of the same super entity set have the same keys the same attributes the same constraints the same natural joins with their super entity set All of the above None of the above the condition A = B in a WHERE clause of an SQL query, where A is an attribute in relation R and B an attribute in relations S, is true for all values of A and B where A = B for all values of A and B where A = B except when A has a NULL value for all values of A and B when? A = B except when B hits a NULL value for all values of A and B where A = B except when A and B have NULL values All of the above None of the above the condition A ALL A in a WHERE clause of an SQL query. where s is a scalar and A an attribute in relation R. is true if s is not equal to any value of A s is not equal to any value of A that is not NULL s NOT IN A s NOT ANY A All of the above None of the above A t constraint that references an attribute A in relation R to attribute B in relation S is checked When changes in R are made When changes in attribute A are made When changes in S are made When changes in attribute B are made All of the above None of the above