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Partial Key: It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.
Alternate Key: All Candidate Keys remaining the Primary Key are called as Alternate Keys.
Artificial Key: If no obvious key either compound or stands alone is available, then the last resort is to simply give a key, by assigning a distinct number to every occurrence or record. Then this is called as developing an artificial key.
Compound Key: If no single data component uniquely identifies occurrences within a developed, then combining multiple components to make a distinct identifier for the construct is called as creating a compound key.
Natural Key: When one of the data components stored within a construct is used as the primary key, and then it is known the natural key.
Selective replication: This is a combination of generating small fragments of relation and replicating them rather than a entire relation. The data should be fragmented on require
The insertion of a tuple in the aim of reference does not cause any destruction. Though, insertion of a tuple in the relation in which, we has the foreign key, for instance, in ASS
Single-Valued Dependencies A database is a collection of related information and it is therefore inevitable that some items of information in the database would depend on some
What are domain constraints? A domain is a set of values that might be assigned to an attribute .all values that appear in a column of a relation must be taken fro
Given the following relations TRAIN (NAME, START, DEST) TICKET (PNRNO., START, DEST, FARE) PASSENGER (NAME, ADDRESS, PNRNO.) Write SQL expressions for the following queries: No
Explain the Concept of Two-phase Locking It concerns the positions of locking and unlocking operations in each transaction. In this protocol every transaction issue lock and u
Evaluate: a.When transactions T1 and T2 are in a deadlock, one of the transactions will eventually implement to completion and let the other one continue implementation. b.
What is horizontal fragmentation? Horizontal fragmentation divides the relation by assuming every tuple of r to one or more fragments
List some instances of collection types? a) sets b) arrays c) multisets
Prove that a relation which is 4NF must be BCNF. Ans Let R be in 4NF. Suppose it is not in BCNF. Hence, there exists an FD X→Y in R such that x is not a super key. Although
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