What is a foreign key, Database Management System

Assignment Help:

What is a foreign key, and what is it used for?

A foreign key is used to establish relationships between relations in the relational model. Technically, a foreign key is a column (or columns) appearing in one relation that is (are) the primary key of another table. Although there might be exceptions, the values in the foreign key columns usually must correspond to values existing in the set of primary key values. This correspondence necessity is created in a database using a referential integrity constraint on the foreign key.

 

 


Related Discussions:- What is a foreign key

DBMS, give some example real life situation where DBMS are most suitable

give some example real life situation where DBMS are most suitable

Create a subroutine, 1. Create a subroutine that does the remote blast on t...

1. Create a subroutine that does the remote blast on the file protein.fa. 2. Pass that returned files from the blast to another subroutine that parses the output and sends it to

What are the concurrency issues, Concurrency issues Data integrity...

Concurrency issues Data integrity: Threads accessing same object need to be synchronized, such as: banking account. Deadlock: One or more threads in system are perman

Query to delete constraint from alter table, A constraint named less_than_2...

A constraint named less_than_20 was defined on the field date_of_birth of table student. Delete this constraint. ALTER TABLE student DROP CONSTRAINT less_than_20;

Mysql, he SQL query that will return the order number, quantity ordered, pr...

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

Abap/4 statements to access internal tables without header, What should be ...

What should be declared explicitly in the corresponding ABAP/4 Statements to access internal tables without header lines & why? Work Area. This is needed as the Work Area is

Distributed query and transaction processing, Distributed query and transac...

Distributed query and transaction processing a.  Construct a query around any one of the functional divisions you made in 4a such that if executed in the distributed design of 4

Why do you go for sorting your query results, Why do you go for sorting you...

Why do you go for sorting your query results? SQL SELECT command to fetch data from MySQL table. Whenever you select rows, the MySQL server is free to return them in any order

Employee elation with information, Consider a database application that dea...

Consider a database application that deals with an Employee relation with information such as SIN, name, data of birth (DOB), and DID (the ID of the department at which the employe

Dataware house, ) Define a job scheduling strategy that will meet business ...

) Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a picto

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