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4 Cards in this Set
- Front
- Back
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Which of the following would make a view non-updateable? select a. The defining query references multiple base relations b. The view contains all of the required columns in the underlying base relations c. One or more of the view's columns is computed by an aggregate function d. DISTINCT is specified in the select statements of the defining query e. The defining query contains group by clauses |
a. The defining query references multiple base relations c. One or more of the view's columns is computed by an aggregate function d. DISTINCT is specified in the select statements of the defining query e . The defining query contains group by clauses |
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What is the advantage of the view materialization over view resolution? |
After the first execution of the defining query, it stores the view as a temporary table, thus obviating the need to re-execute the defining query each time the view is requested. |
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Foreign key(ownerNo) references privateOwner on delete cascade; |
If a row is deleted from the privateOwner table, delete any row in the propertyForRent table that has a matching ownerNo |
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What does the following constraint do? Check(not exists(select courseId from studentcourses group by couseId having count(*) < 10)); |
It ensure that no course has an enrollment of less than 10 students. |
