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!
Define entity integrity and referential integrity. How does SQL allow specification of these?
Ans: Entity Integrity Rule- If the attribute A of relation R is a prime attribute of R after that A cannot accept null values.
Referential Integrity Rule- In referential integrity, it is made sure that a value that appears in one relation for a given set of attributes as well appears for a particular set of attributes in another relation.
In SQL, referential integrity and entity integrity rules are implemented as constraints on the relation known as reference Key constraint and primary Key constraint correspondingly.
These constraints can be fixed with relation at the time of creation of the relations or after the creation of the relations by altering the definition of the relations. For instance:
These are designed to reduce the effects of a database failure and make sure a database is restored to a consistent state if a failure does arise. Manual backup/restore utilities n
Explain the Role of a database administrator a. Defining the Schema The DBA describes the schema which consists of the structure of the data in the application. The DBA
Q. Describe how an ER schema can be represented by relation schemas and constraints arising from ER design can be mapped to constraints on a relation schema. The entity rela
List the drawbacks of relational database system A) Repetition of data B) Inability to s certain information.
difference between MIS and DSS
complete assignment on the above title.
Nested Queries Let us see some more complex queries in this section. Sub-queries: Some of the basic concerns of sub-queries are: A sub-query is a SELECT statemen
Write short note on Data models? Data models: A data model is an abstract model which elaborates how data is represented and accessed. The term data model has two commonly ac
Draw entity relationship diagram for the following scenario. A university has many departments whereas each department belongs to that particular uni. That uni has also many bui
courier company er-diagram
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