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.
An example of a weak entity is Staff because the availabilityID cannot be uniquely identified unless it is used in conjunction with the foreign key known as availabilityID in the A
What is a PROJECT operation? The project operation is a unary operation that returns its argument relation with particular attributes left out. Projection is shown by pie (π).
Explain P command in the respect of QBE? P: It is the command in which is used to print (logically display) the value of the attribute in whose cell it is writ
How do I use strap on?#
Define multivalued dependency and 4NF. Ans: Multivalued Dependency - Assume R be a relation schema and let α ⊆ R and β ⊆ R. The multivalued dependency α →→β holds o
Describe the static hash file with buckets and chaining and show how insertion, deletion and modification of a record can be performed. In static hash file organization, the wo
Need For Distributed Database Systems A distributed database is a set of database kept on multiple computers that appears to applications as a one database. As a result, an app
Define cardinality and participation constraints on a relationship type, completeness constraint on generalization. Ans: Cardinality defines the number of entities to wh
Explain Foreign Key? Foreign Key - Let there are two relations (tables) R and S. Any candidate key of the relation R that is referred within the relation S is known as the fo
Explain Network Model in DBMS? Network Model - It was formalised within the late year of 1960s through the Database Task Group of the Conference on Data System Language (DBTG
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