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Explain Two phase locking protocol
A transaction is consider as to follow the two-phase locking protocol if all locking operations precede the first unlock operation in the transaction. Such type of transaction can be divided into two phases: and expanding or growing (first) phase, throughout which new locks on items can be acquired but none can be released; and a shrinking (second) phase, throughout which existing locks can be released but no new locks can be obtained. This two-phase protocol can make sure the serializability because all the data items needed by a transaction will be locked at the starting of the transaction and if other transaction needs to use those data items then it has to wait till they become unlocked.
in case of functional dependencies how we get the higher normal form.
Explain the terms primary key, candidate key, alternate key and secondary key. In the given table identify every key? STUDENT(SID,Regno, Name, City) Primary Key: The prim
Consider the following relational database: STUDENT (name, student#, class, major) COURSE (course name, course#, credit hours, department) SECTION (section identifier, course#, sem
a) Suppose we updated the catalog tables in real time, that is, after every update, insert, or delete SQL statement were executed-rather than only running RUNSTATS once every few
Need For Distributed Database Systems A distributed database is a set of database kept on multiple computers that appears to applications as a one database. As a result, an app
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Consider the table student and list names of students in the departments other than maths and computer. SELECT std_name FRM student WHERE dept_name NOT IN (‘Maths','Computer);
Explain Superkey Ans: A superkey is described in the relational model of database organization like a set of attributes of a relation variable for which it holds that in all re
What is a SELECT operation? The select operation selects tuples that please a given predicate. We use the lowercase letter σ to denote selection.
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