1. A foreign key can make reference to ) A. an attribute that is a primary key of another table B. an attribute tha table C. both A and B D. neither A nor B t is a primary key of the same 2.A relation has only one A. superkey B. candidate key C. primary key D. foreign key 3.A set of attributes that, taken collectively, allow us to identify uniquely a tuple in the relation is called A. super key B. primary key C. candidate key D foreign key 4 which it holds that: no two distinct tuples in the relation can have the same values for the attributes in this set. is a minimal set of attributes for A. Candidate key Superkey C. Foreign key D. Primary key 5.SQL language use the statement to delete a table from database A. REVOKE B. DELETE C. REMOVE D DROP 6.If table S has M rows, table T has N rows, then the Cartesian product of S and T has A. M*N B. M-N C. M+N D. M+N-1 7.If table S has M columns, table T has N columns, then the Cartesian product of S and T has columns. rOws. is not the basic notions of the E-R model A. entity attribute 9.If the mapping cardinality from entity set S to entity set T is one to many, then an entity of T is associated with entity(entities) of S. A. one B. at most one C. at least one D. many B. relationship C. degree