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.
Cardinality shows the number of instances of an entity associated with another entity participating in a relationship. Depend on the cardinality binary relationship can be further
If the insertion violates one or more constraints, then two alternatives are available: Default option: - Insertion can be discarded and the reason of refusal can also be ex
he SQL query that will return the order number, quantity ordered, price each and total cost of an order (quantity * price each) from the order details table. Label the calculated c
The traffic data mgmt. systems infrastructure plan describes the software, hardware, data network, and other elements that will support the TDMS. The infrastructure plan is based o
What are referential integrity constraints? A value that appears in single relation for a given set of attributes also appears for a particular set of attributes in another rel
Explain the concept of generalization and aggregation in E_R diagrams. Give one example for each one of them? Generalization: Consider extending the entity set account throug
Draw an ER diagram that represents the information described below. Show all entity sets, relationship sets, primary keys, and the mapping cardinality of the relationship sets.
Explain the following functions of Oracle with suitable examples: (i) To_Char( ) (ii) Count( ) (iii) Trim( ) (iv) Length( ) Ans: (i) To_char( ): The TO_CHAR function conver
How can Redundant Associations be done It can be done by asking questions: i) Is there a specific arrangement of network which would optimize critical aspects of completed
Define the terms i) Key attribute ii) Value set Key attribute: An entity type usually has an attribute whose values are exact from each individual entity in the collection. Su
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd