Problem 1 Database Concepts ( 20 points, 2 points each) (1) A weak entity can be identified uniquely only by considering some of its attributes in conjunction with the primary key of another entity, which is called the identifying owner. False (2) For a given view, an INSERT or UPDATE may change the underlying base table so that the resulting (i.e., inserted or modified) row is not in the view. False (3) The natural join of two relations R(A,B) and S(C,D), which have no common attribute, is equivalent to their full outer join. False (4) In a table, there is exactly one candidate key, but there can be multiple superkeys. False (5) Every relationship in an ER diagram must translate to an individual relation in the relational model. True False (6) Two relation instances are said to be union-compatible on the only condition that they have the same number of fields. True False (7) SQL supports the creation of assertions, which are constraints not associated with any single table. True False (8) Only columns that appear in the GROUP BY clause can appear in the HAVING clause, unless they appear as arguments to an aggregate operator in the HAVING clause. True False (9) The expression, COUNT (), handles null values just like other values; that is, they get counted. False (10) Once the schema of a database is set, it cannot be changed. True False