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CS6400 - Exam Study Guide Questions Solved 100% Correct | Verified Answers
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CS6400 - Exam Study Guide Questions Solved 100% Correct | Verified Answers
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CS6400 - Exam Study Guide Questions Solved 100%Correct | Verified Answers
natural join - ✔✔Links tables by selecting only the rows with common values in their
common attributes
Theta join - ✔✔A join operator that links tables using an inequality comparison operator (<,
>, <=, >=) in the join condition. All attributes are preserved, also an inner join
Left outer join - ✔✔A join that includes all of the rows from the first table in the query and
only those records from the second table that match the join field in the first table.
Cartesian product - ✔✔combines every tuple in the two operands
Divideby - ✔✔For A to be in the table it must match a value in the divisor
Rename - ✔✔useful to control natural join, theta join, etc.
what is SQL based on? - ✔✔tuple calculus
predicates - ✔✔built from atoms.
range expression - ✔✔t is a tuple of relation R
attribute value - ✔✔value of t on attribute a
constant - ✔✔c is a constant
, atoms - ✔✔range expression, comparison of two attributes, or compare attribute of a tuple
to a constant
Predicate - ✔✔an atom is predicate. if P1 and P2 are predicates, so are (P1), not(p1), P1 or
P2, P1 and P2, P1=>P2
if P(t) is a predicate t is a free variable in P and r is a relation - ✔✔then there is a t and r that
satisfies p as a predicate
cardiniality - ✔✔number of rows
degree - ✔✔number of columns
Entity type ET with single value property - ✔✔relation ET has B as an attribute
Entity type ET with identifying property A - ✔✔relation ET there will be an attribute A that is
a primary key
Entity ET with composite C, made up D and E - ✔✔Relation only includes D and E, C is lost
Relation model is inherently: - ✔✔flat!
Entity ET with identifying property A and multi-value property F - ✔✔For each F a brand new
relation is created, called ET-F. insert identifying property so combination of A and F is a
composite key in ET-F
1:1 relational mapping - ✔✔B in ET1 is a foreign key to B in ET2. or A in ET2 is a foreign key
to A in ET1. both are acceptable.
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