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Differentiate between Key and superkey?
Key and superkey - A key a single attribute or a combination of two or more attributes of an entity set in which is used to identify one or more instances (rows) of the set (table). If we add a few additional attributes to a primary key then in which augmented key is known as super key. Thus, the primary key is the minimum super key.
Discuss the problem of Spurious tuples and how we may prevent it. Ans: A spurious tuple is, mainly, a record in a database that gets created while two tables are joined bad
Define Shared locks? Ans: Shared lock: Throughout concurrent execution of transactions, earlier than a transaction can access a data item, it has to obtain a lock on it. Now he
What are uncommitted modifications? The immediate-modification technique permits database modifications to be output to the database whereas the transaction is still in the act
Attribute Preservation This is a easy and obvious necessity that includes preserving all the attributes that were there in the relation that is being decomposed.
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);
Object Oriented model :An object has values stored in instance variables within the object. An object also has bodies of code that execute on the object. These bodies of code are
why three level architecture had been developed/
Explain the B + tree? B + tree is a type of tree which denotes sorted data in a way that permits for efficient insertion, retrieval and removal of records, each of which is
Short Note on mid Square Method of hashing? Mid square method of hashing: In the method midsquare hashing, the key is squared and the address selected from the center of the s
What is called a query -execution engine? The query implementation engine takes a query evaluation plan, implements that plan, and returns the answers to the query.
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