CS6400 Exam 3 Questions with Detailed Verified Answers
Natural Join
Ans: The result of this is the set of all combinations of tuples in R and S that are equal
on their common attribute names. A special case of an equijoin.
Left Outer Join
Ans: A construct operator which results in the set of all combinations of tuples in R and
S that are equal on their common attribute names, in addition (loosely speaking) to
tuples in R that have no matching tuples in S.
Insert
Ans: A basic SQL operation in which new records are added to a table.
Delete
Ans: A basic SQL operation in which existing records are removed from a table.
Update
Ans: A basic SQL operation in which existing records are changed in a table.
Select *
Ans: A basic SQL operation in which existing records are chosen from a table.
Select Distinct
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Ans: A basic SQL operation in which only unique existing records are chosen from a
table.
Intersect
Ans: Set operator which includes all tuples that are in both R and S.
Union
Ans: Set operator which includes all tuples that are either in R or in S or in both R and
S. Duplicates are removed.
Union All
Ans: set operator which includes all tuples that are either in R or in S or in both R and
S. Duplicates are not removed.
Count(*)
Ans: SQL function which returns the number of rows that matches the specified
criteria.
Group By
Ans: SQL operator which rolls up the result set by one or more columns.
Equijoin
Ans: A theta join using the equality operator
Difference / Minus
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