What is foreign key, Database Management System

Assignment Help:

What is foreign key?

Foreign Key - Let there are two relations in tables R and S. Any candidate key of the relation R that is referred in the relation S is known as the foreign key in the relation S and referenced key within the relation R. The relation R is also known as parent table and relation S is also known as child table.


Related Discussions:- What is foreign key

Er diagram, Design a generalization–specialization hierarchy for a motor-ve...

Design a generalization–specialization hierarchy for a motor-vehicle sales company. The company sells motorcycles, passenger cars, vans, and buses. Justify your placement of attrib

The data of a view is not physically stored, The data of a view is not phys...

The data of a view is not physically stored, but derived from one or more tables. True the data of a view is not physically stored

Vertical fragmentation, Vertical Fragmentation- Vertical fragmentation grou...

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

Deletion operation - update operations, By using the delete operation some ...

By using the delete operation some consisting records can be deleted from a relation. To delete some definite records from the database a condition is also specified based on which

Write the sql code, Express the following queries in SQL: (a) Write the...

Express the following queries in SQL: (a) Write the SQL code that will create ALL the four tables given in the appendix. Your answer should not contain the primary key and

Using column aliases-data manipulation language, Using Column aliases E...

Using Column aliases Example: To print column names as NAME and ANNUAL SALARY SELECT ENAME "NAME", SAL*12 "ANNUAL SALARY" FROM EMP;

Give two profit of reuse of code, Give two profit of Reuse of Code. Re...

Give two profit of Reuse of Code. Reusing the implementation . Place existing class directly inside a new class. The new class can be made up of any number and type of the oth

What is an entity relationship model, What is an entity relationship model?...

What is an entity relationship model?  The  entity  relationship  model  is  a  collection  of  basic  objects  known as entities  and  relationship  between  those objects. An

What is the need of a log in a dbms, What is the need of a log in a DBMS? B...

What is the need of a log in a DBMS? Briefly describe the various types of records that are normally present in a log.            Ans:  The system log, which is generally writt

Explain physical and logical independence, Define Physical and Logical inde...

Define Physical and Logical independence  Ans: Physical data independence: The ability to modify physical level without causing application program to be rewritten. Logic

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd