Suppose relation R(A,B,C,D,E) has the following functional dependencies: A -> B B -> C BC -> A A ...
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Suppose now that R(A,B) and S(A,B) are two relations with r and s tuples, respectively (again, not necessarily distinct). If m is the number of (not necessarily distinct) tuples in the result of the SQL query:
R intersect S;
Then which of the following is the most restrictive, correct condition on the value of m?
Suppose now that R(A,B) and S(A,B) are two relations with r and s tuples, respectively (again, not necessarily ...
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Suppose relation R(A,B) currently has tuples {(1,2), (1,3), (3,4)} and relation S(B,C) currently has {(2,5), (4,6), (7,8)}. Then the number of tuples in the result of the SQL query:
<i>SELECT *
FROM R NATURAL OUTER JOIN S; </i>IS:
Suppose relation R(A,B) currently has tuples {(1,2), (1,3), (3,4)} and relation S(B,C) currently has {(2,5), (4,6), (7,8)}. Then ...
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Suppose we wish to find the ID’s of the employees that are managed by people who are managed by the employee with ID 123. Here are two possible queries:
I.SELECT ee.empID
FROM Emps ee, Emps ff
WHERE ee.mgrID = ff.empID AND ff.mgrID = 123;
II.SELECT empID
FROM Emps
WHERE mgrID IN
(SELECT empID FROM Emps WHERE mgrID = 123);
Which, if any, of the two queries above will correctly (in SQL2) get the desired set of employee ID’s?
Suppose we wish to find the ID’s of the employees that are managed by people who are managed ...
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Consider a relation R(A,B,C,D,E) with the following functional dependencies:
ABC -> DE and
D -> AB
The number of superkeys of R is:
Consider a relation R(A,B,C,D,E) with the following functional dependencies: ABC -> DE and D -> AB The number ...
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There are two functional dependencies with the same set of attributes on the left side of the arrow:
A->BC
A->B
This can be combined as
There are two functional dependencies with the same set of attributes on the left side of the arrow: A->BC A->B This ...
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Inst_dept (ID, name, salary, dept name, building, budget) is decomposed into
instructor (ID, name, dept name, salary)
department (dept name, building, budget)
This comes under
Inst_dept (ID, name, salary, dept name, building, budget) is decomposed into instructor (ID, name, dept name, salary) department ...
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The relation employee(ID,name,street,Credit,street,city,salary) is decomposed into
employee1 (ID, name)
employee2 (name, street, city, salary)
This type of decomposition is called
The relation employee(ID,name,street,Credit,street,city,salary) is decomposed into employee1 (ID, name) employee2 (name, street, city, salary) This type of decomposition ...
View QuestionWhich of the following is not Armstrong’s Axiom?
a) Reflexivity rule b) Transitivity rule c) Pseudotransitivity rule d) ...
View QuestionWe can use the following three rules to find logically implied functional dependencies. This collection of rules is called
a) Axioms b) Armstrong’s axioms c) Armstrong d) Closure Answer: b
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