Question

If a relation schema is in 3nf, it is in BCNF. True/False Foreign key values can...

If a relation schema is in 3nf, it is in BCNF.

True/False

Foreign key values can be null.

True/False

In a table there is exactly one candidate key, but there can be multiple super keys.

True/False

Any candidate key is a super key

True/False

The primary key of a relation may have more than one attribute. However, a foreign key of    a relation must have only one attribute.

True/False

Given relation R1, where R1 contains N1 tuples and a is an attribute of R1, the minimum    possible size in tuples of σa=5(R1)

True/False

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Answer #1 
If a relation schema is in 3nf, it is in BCNF.
False

Foreign key values can be null.
False

In a table there is exactly one candidate key, but there can be multiple super keys.
True

Any candidate key is a super key
True

The primary key of a relation may have more than one attribute. However, a foreign key of    a relation must have only one attribute.
False

Given relation R1, where R1 contains N1 tuples and a is an attribute of R1, the minimum    possible size in tuples of σa=5(R1)
False
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