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!
Explain entity integrity and referential integrity rules within relational model. Show how these are realized in SQL?
Entity Integrity Rule - No primary key value could be null.
Referential Integrity Rule - In referential integrity, it is ensured in which a value which appears in one relation for a given set of attributes also appears for a certain set of attributes within another relation.
In SQL, entity integrity and referential integrity rules are implemented as constraints on the relation known as primary key constraint or reference key constraint corresponding. These constraints can be specified along with relation at the time of creation of the relations or after the creation of the relations through altering the definition of the relations. For instance:
CREATE TABLE DEPT
(DEPTNO NUMBER PRIMARY KEY,
DNAME VARCHAR2(15));
CREATE TABLE EMP
(EMPNO NUMBER PRIMARY KEY,
20
ENAME VARCHAR2(15),
JOB VARCHAR2(10),
DEPTNO NUMBER REFERENCES DEPT(DEPTNO));
what is correlation in nested query
Which operation is used if we are interested in only certain columns of a table? PROJECTION operation is used if we are interested in only certain columns of a table.
Describe integrity and security? a) Domain constraint b) Referential integrity A value that appears in one relation for a given set of attributes also appear fo
In which form of relational database developer refers to a record? In a tuple form of relational database developer refers to a record.
I need to Map an E-R diagram to a relational schema
Control as a State Machine Engine First let us define the state machine: "the state machine is a machine which is an object but not an application object. It is a part of lang
What is a Transaction? A transaction is an event which happens on the database. Generally a transaction reads a value from the database or writes a value to the database. If y
Need an expert in ER database theoretical and modeling database system Project Description: Need an expert in ER database theoretical and modeling database systems? Skills
What is a data dictionary? Data Dictionary is a main source of data in a data management system. Its major function is to carry the creation and management of data definition
Define shadow paging. An alternative to log-based crash recovery method is shadow paging. This technique requires fewer disk accesses than do the log-based methods.
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