Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
It defines that no primary key value can be null. This is as the primary key is used to recognize individual tuple in the relation. So we will not be able to recognize the records uniquely containing null values for the primary key attributes. This constraint is specified on single individual relation.
Example: Let R be the Table
A#
B
C
Null
B1
C1
A2
B2
C2
B3
C3
A4
B4
A5
C5
Note:
1) '#' shows the Primary key of a relation.
In the relation R above, the primary key has null values in the tuples t1 & t3. NULL value in primary key is not allowed, therefore, relation instance is an invalid instance.
Hardware failure : Hardware failures are the failures when some disk or hardware chip fails. This may result in loss of data. One such trouble can be that a disk gets damaged and
What is known as heap file organization? In the heap file organization, any record can be placed anywhere in the file where there is space for the record. There is no ordering
Problem 1. Describe the following a) Advantages of Database Systems b) Functions of a DBMS Explanation of part (a) and (b) 2. Explain the following concepts w
Question: (a) Why is it important to know the architecture rather than to start requirement capture when designing a large scale system? (b) Who are the different people in
Flights(FlightNo, DeptDateTime, Origin, ArrivalDateTime, Destination, Capacity, SoldSeats) Tickets(FlightNo, Seat, CustID) Where - flightNo is the PK of the flights table - DeptDa
What is trigger Triggers are statements that are implemented automatically by the system as the side effect of a change to the database.
Suppose an instruction takes 1 nanosecond to execute (on average), a page fault takes 20 microseconds of processor time, and it takes 300 microseconds of disk time to read or write
What are the costs to be considered when a transaction has to be rolled back when recovering from deadlock? Ans: A few transaction will must rolled back (made a victim)
List two restrictions that are applied on the modification (updation, insertion or deletion) of base tables through view. Ans: The two restrictions are: 1. If a view
What is normalization? It is a method of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to attain the properties (1).Minim
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd