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.
Vertical Fragmentation- Vertical fragmentation groups together only those attributes in a relation that are used jointly by various important transactions. A vertical fragment is d
Why is database design important?
how to operate database in access ?
Define null values. In some cases a certain entity may not have an applicable value for an attribute or if we do not know the value of an attribute for a certain entity. In the
What's the difference between a primary key and a unique key? Both primary key and unique key enforces uniqueness of the column on which they are explained. But by default prim
Which is the properties of entities? Attributes is the properties of entities.
Assignment #1 Data Management The questions on this exam are based on the Baxter Aviation case scenario. 1. (5 points) The systems analyst proposes the following two relationshi
What are the two methods for dealing deadlock problem? The two procedures for dealing deadlock problem is deadlock detection and deadlock recovery.
ER diagram on cosmetics
Consider the join of a relation R with relation S. If R has m tuples and S has n tuples, then the maximum size of join is: If R has m tuples and S has n tuples then maximum siz
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