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!
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.
A database is a set of data. But, is the data kept in a database trustworthy? To answer that query we must first answer the question. What is integrity? Integrity simply means t
These are the binary operations; i.e., each is applied to two relations or sets. These two relations can be union compatible excluding in case of Cartesian product. Two relations R
Differentiate between Key and superkey? Key and superkey - A key a single attribute or a combination of two or more attributes of an entity set in which is used to identify o
What do you mean by persistence? How you will make your data persistent? Persistent data is the data, which has a longer lifetime than program which has created it. Enabling th
List any two disadvantages of a database system ? The disadvantages of database system are: • Database systems are difficult, complex, and time-consuming to design. • Substanti
Representing complex relationship among data A database may contain varieties of data interrelated to each other in numerous ways. A DBMS must have the capability to represent
Funky Festivals Specification Funky Festivals organise music festivals which take place at various venues throughout the UK. A venue needs to be booked before a Festival can t
Example : Search the name, department number and salary of employees drawing minimum salary in that department. SELECT ENAME, SAL, DEPTNO FROM EMP WHERE SAL IN (SELECT MI
A Relation Schema represented by R(A1, A2, ..., An) is made up of the relation name the list of attributes and R Ai that it contains. A relation is described as a set of tuples
Creating views with check option : This option limits those updates of data values that cause records to go off the view. The following instance tells this in more detail: Examp
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