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Define Partial Key and Primary Key
A partial key, also known as discriminator, is the set of attributes which can uniquely identify weak entities that are related to similar owner entity. Primary key is a unique key but not comprise null values. An entity set can comprise at most one primary key.
Explain Candidate key? Candidate Key - A candidate key is a minimal superkey, that can be used to uniquely identify a tuple in the relation.
An instance of relational schema R (A, B, C) has distinct values of A including NULL values. then A is a candidate key or not? If relational schema R (A, B, C) has distinct val
Compare the Nested-loop join and block-nested loop join Ans: Nested loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r where b
Why were functional methods fashionable in early days? These are inspired directly by computer architecture and thus popular among computer scientist in early days. The divisio
explain normalisation
Suppose R is a relation with attributes A1, A2,..., An. As a function of n, tell how many superkeys R has, if: 1.1 The only key is A1. 1.2 The only key is A1 and A2. 1.3 The o
Why containment is important in oosystems? Containment is an significant concept in oosystems because it allows dissimilar users to view data at different granularities.
Describe an data dictionary? A data dictionary is a data structure which keeps meta data about the structure of the database ie. the schema of the database.
When is a transaction rolled back? Any changes that the aborted transaction made to the database must be uncompleted. While the changes caused by an aborted transaction have be
In a job interview with a branch manager of a bank that operates in multiple Canadian provinces and the Yukon, you learn that all of the information is captured in real time in a s
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