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@ []Query Q 2.9.1: Find the names of departments that had a budget greater than $90K
during the period when Di managed them.
Answer: ``Toy''.
Category: (Projected, None) / (Containment, Element, Computed) / (=, Constant)
(=, Constant) (=, Foreign)
The employee with name Di has managed the Toy department since 1/1/1982 and during that period the budget was always greater than $90K. The category ``(Containment, Element, Computed)'' indicates that a containment based predicates is used on element-valued arguments which are both derived from the valid-times of stored facts. The non-temporal selection predicates test for equality between the employee name and ``Di'', the equality between the same attribute and the foreign key of the Dept relation and the comparison between the department budget and the amount of $120K.
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@ []Query Q 2.9.2: Find Ed's salary during the periods he worked in the same
department as Di's.
Answer: $20K, $30K, $40K.
Category: (Projected, None) / (Containment, Element, Computed) / (=, Constant)
(=, Single) (=, Constant)
The second non-temporal selection predicate belonging to the class ``(=, Single)'' test the equality between the department of Ed and Di.
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@ []Query Q 2.9.3: Find the names of the departments which Ed worked in earning
$40K.
Answer: ``Toy'',``Book''.
Category: (Projected, None) / (Containment, Element, Computed) / (=, Constant)
(=, Constant)
The predicates belonging to the class ``(=, Constant)'' indicate the selection of the employee Ed and test the equality between his salary and the amount of $40K.
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@ []Query Q 2.9.4: Find Ed's name after he left the Toy department.
Answer: ``Edward''.
Category: (Projected, None) / (Ordering, Element, Computed) / (=, Constant) (=,
Constant)
An ordering based predicate is used to select the name of employeee Ed with valid-time following the period he worked for the Toy department.
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@ []Query Q 2.9.5: Find Ed's skills when he worked in the Toy department.
Answer: ``driving'',``filling'',``typing''.
Category: (Projected, None) / (Containment, Element, Computed) / (=, Constant)
(=, Foreign) (=, Constant)
The non-temporal predicate of the class ``(=, Constant)'' indicates the selection of the employee with name Ed; ``(=, Foreign)'' indicates the selection of the skills of such employee and ``(=, Constant)'' indicates the selection of the Toy department.
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@ []Query Q 2.9.6: Who ever worked in a department longer than their manager while
in that department?
Answer: ``None''
Category: (Projected, None) / (Containment, Element, Computed) /
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@ []Query Q 2.9.7: What new skills did Ed hold after he had changed his name to Edward?
Answer: ``None''
Category: (Projected, None) / (Ordering, Element, Computed) / (=, Constant) (=, Constant)
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@ []Query Q 2.9.8: What were Toy's departmental budgets when it was managed by Di?
Answer: ``150K'', ``200K'' and ``100K''
Category: (Projected, None) / (Containment, Element, Computed) / (=, Constant) (=, Constant)