Given the following relation S(SNO,SNAME,CITY) write a query to update the value of CITY to KANPUR for the supplier S1
Answer: C
Correct answer: UPDATE S SET CITY = KANPUR WHERE SNO=S1
The UPDATE statement has a fixed shape: UPDATE table SET column = value WHERE condition. SET is required before the assignment and WHERE before the condition; FOR and RENAME have no place in it.
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The division operator divides a dividend A of degree m+n by a divisor relation B of degree n and produces a result of degree
Answer: D
Correct answer: m
Division cancels the divisor's attributes: dividing a relation of degree \( m+n \) by one of degree \( n \) leaves a result of degree m. The result contains those values of the remaining m attributes that appear with every tuple of the divisor.
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Which of the following is not comparison operator?
Answer: C
Correct answer: =<
The comparison operators are \(=\), \(<\), \(>\), \(<=\), \(>=\) and \(<>\). The form =< has its symbols reversed and is not valid; the correct spelling is \(<=\).
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A relational database developer refers to a record as
Answer: B
Correct answer: a tuple
In relational terminology a row is a tuple, a column is an attribute, and the table as a whole is a relation.
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A logical schema
Answer: C
Correct answer: is a standard way of organizing information into accessible parts
The logical schema describes the data as tables, attributes and relationships - the structure a user or programmer works with. How those tables are actually laid out on disk is the physical schema, which is a separate description.
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What is data integrity?
Answer: B
Correct answer: It is the data contained in database that is accurate and consistent
Integrity means the data is correct and internally consistent, which is what constraints, transactions and referential rules exist to protect. Security is a separate property, concerning who may see the data rather than whether it is right.
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Which of the following is true for network structure?
Answer: A
Correct answer: It is a physical representation of the data.
The network model links records with physical pointers, so the structure the programmer sees is the structure on disk. That is its chief weakness against the relational model, and it is also why it is not conceptually simple.
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A top-to-bottom relationship among the items in a database is established by a
Answer: A
Correct answer: Hierarchical schema
A hierarchical model arranges records in a tree, so each child has exactly one parent and the structure reads from top to bottom. A network model allows several parents, and a relational model has no such ordering at all.
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E-R Modeling is achieved by using ____ diagrams
Answer: D
Correct answer: E-R
Entity-relationship modelling is expressed in E-R diagrams: rectangles for entities, ovals for attributes, diamonds for relationships. DFDs model processes and Gantt charts schedules.
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In multiple granularity of locks SIX lock is compatible with
Answer: B
Correct answer: IS
A SIX lock - shared with intention exclusive - means the holder is reading the whole subtree and intends to write part of it. Another transaction may still hold an IS lock, since reading is compatible with reading; but IX, S and SIX all conflict, because each would either write where SIX reads or read where SIX intends to write.
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