CECS 323 FINAL STUDY GUIDE
Union - Answers -includes members of either or both sets without duplicates
Minus or Except - Answers -includes only those members of the set on the left side of
the expression that are not contained in the set on the right side of the expression
Intersect - Answers -includes members that are common to both sets
Union All - Answers -works like UNION (includes members of either or both sets)
except it keeps duplicate rows in the set
Set Operations - Answers -operations that aggregate two or more result sets. In order
to do this all tables must have to contain the same number of columns of the same type
What does it mean for a transaction to be ACID? - Answers -for a transaction to be
ACID, the execution of each transaction must maintain the relationship between the
database state and the enterprise state
Atomicity - Answers -transaction is either performed in its entirety or not performed at
all
Isolation - Answers -transaction should appear as though it is being executed
separately from other transactions
Consistency - Answers -transaction must take the database from one valid state to
another
Durability - Answers -changes applied to the database by a committed transaction must
persist, even if the system fails before all changes reflected on the disk
Serializable Schedule - Answers -actual execution sequence of two or more concurrent
transactions where running transactions T1 and T2 is the same effect as either T1;T2 or
T2;T1.
subclass - Answers -when one or more attributes of a class are characteristics of only
some individuals of that class, but not others
subquery - Answers -Sometimes you don't have enough information available when
you design a query to determine which rows you want. In this case you'll have to find
the required information with a subquery
