Key to represent relationship between tables is called
Answer: C
Correct answer: foreign key
A foreign key is a column whose values must appear as a primary key in another table, and that requirement is what represents the relationship between the two. A primary key identifies rows within one table only.
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The values of the attribute describes a particular
Answer: C
Correct answer: Entity instance
A particular set of attribute values describes one particular thing - one entity instance, or occurrence. The entity set is the collection of all such instances of the same type.
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The clause in SQL that specifies that the query result should be sorted in ascending or descending order based on the values of one or more columns is
Answer: B
Correct answer: Order by
ORDER BY sorts the result, taking ASC or DESC and one or more columns. GROUP BY collects rows into groups and HAVING filters those groups; neither of them sorts.
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______contains information that defines valid values that are stored in a column or data type.
Answer: B
Correct answer: Rule
A rule is bound to a column or a user-defined data type and specifies which values are acceptable there. A default supplies a value when none is given, and an index affects only how rows are found.
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A ____ key specifies a uniqueness constraint that no two distinct tuples in any state r of relation R can have the same value for super key.
Answer: D
Correct answer: Super
A super key is any set of attributes whose values are unique across the relation. A candidate key is a super key with no redundant attribute in it, so every candidate key is a super key but not the reverse.
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The drawback of shadow paging technique are
Answer: D
Correct answer: All of these
Shadow paging avoids undo and redo but pays for it in three ways: committing means switching page tables and flushing, related pages become scattered because updates are written elsewhere, and the superseded pages have to be reclaimed afterwards.
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Isolation of the transactions is ensured by
Answer: C
Correct answer: Concurrency control
Isolation - that each transaction behaves as though it ran alone - is what the concurrency control component provides, through locking or timestamping. Atomicity and durability are the transaction and recovery managers' business.
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HSAM stands for .
Answer: B
Correct answer: Hierarchic Sequential Access Method
HSAM is Hierarchic Sequential Access Method, one of the IMS access methods, in which the segments of a hierarchical database are stored in sequential order.
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The ______ operator is used to compare a value to a list of literal values that have been specified.
Answer: A
Correct answer: IN
IN tests whether a value appears in a list, as in \( \text{city IN ('Delhi','Mumbai','Pune')} \). LIKE matches a pattern against a single string and BETWEEN tests a range.
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An advantage of the database management approach is
Answer: C
Correct answer: data is integrated and can be accessed by multiple programs
The point of the database approach is that data is held once, in one place, and shared: many programs read the same integrated store instead of each keeping its own file. Redundancy falls rather than rises, and the data becomes independent of the programs.
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