If a transaction T has obtained an exclusive lock on item Q, then T can
Answer: C
Correct answer: both read and write Q
An exclusive lock gives the holder complete access - it may both read and write the item - and excludes every other transaction. A shared lock permits reading only, but allows other readers at the same time.
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Which one is the correct statement? Logical data independence provides the following without changing application programs: (i) Changes in access methods. (ii) Adding new entities in the database. (iii) Splitting an existing record into two or more records. (iv) Changing the storage structure of the database.
Answer: D
Correct answer: (ii) and (iii)
Logical data independence protects programs from changes to the logical structure: adding an entity or splitting a record leaves existing programs working, because they still see the fields they asked for. Changing access methods or the storage structure is a change at the physical level, and immunity to those is physical data independence.
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The full form of GUI is _________
Answer: C
Correct answer: Graphical User Interface
GUI stands for Graphical User Interface - an interface of windows, icons and pointers, as against a command line.
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DBMS is a collection of _____ that enables user to create and maintain a database.
Answer: B
Correct answer: Whenever a 1 is present at an input
NOR is the complement of OR. OR is 1 as soon as any input is 1, so NOR is 0 in that case, and it is 1 only when every input is 0.
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Immediate database modification technique uses
Answer: A
Correct answer: Both undo and redo
With immediate modification a transaction's writes reach the database before it commits, so an uncommitted transaction's changes must be undone after a crash, and a committed transaction's changes that had not yet reached disk must be redone. Deferred modification needs redo only, since nothing is written before commit.
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The clause alter table in SQL can be used to
Answer: D
Correct answer: all of the above
ALTER TABLE covers every change to a table's definition: adding a column, dropping one, and changing a column's type, default or constraints.
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Processed data is called _____
Answer: C
Correct answer: Information
Data are raw facts; once they have been organised, summarised or interpreted so that they mean something, they are information. That is the distinction on which the whole subject rests.
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Assume transaction A holds a shared lock R. If transaction B also requests for a shared lock on R.
Answer: C
Correct answer: It will immediately be granted.
Shared locks are compatible with one another, since reading does not interfere with reading. B would have to wait only if A held an exclusive lock or if B were asking for one.
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Create a table with the following attributes: Employee(EMPNO integer, EMPNAME of 10 characters)
Answer: A
Correct answer: Create table Employee(EMPNO int, EMPNAME char(10));
A ten-character column is declared char(10); String is not an SQL type and a bare string has no length. The table must also be named as the question specifies, which rules out the options calling it Emplo or Emp.
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In a relational schema, each tuple is divided into fields called
Answer: A
Correct answer: Domains
A relation is defined over a set of attributes, each drawn from a domain - the set of permitted values for that field. So the fields into which a tuple divides correspond to the domains of the relation. Relations are the tables themselves, one level up.
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