What is Composite key in DBMS

a combination of multiple Column

a combination of multiple tables

Consider the following schema for products: Product(maker, model, type) PC(model, speed, ram, hd, price) Laptop(model, speed, ram, hd, screen, price) Printer(model, color, type, price) 2. Which manufacturers make laptops with a hard disk of at least 100GB?

Πmaker(σ(Product.model=Laptop.model)∧(hd>=100)(Product × Laptop))

Πmaker(σ(hd>=100)(Product × Laptop))

Πmaker(σ(Product.model=Laptop.model)V(hd>=100)(Product × Laptop))

Πmaker(σ(Product.model=PC.model)∧(hd>=100)(Product × Laptop × PC))

Consider the following schema for products: Product(maker, model, type) PC(model, speed, ram, hd, price) Laptop(model, speed, ram, hd, screen, price) Printer(model, color, type, price) 3. Find the model numbers of all color laser printers.

Πmodel(σ(type='Laser')∧(color='all')(Printer))

Πmodel(σ(type='Color Laser')(Printer))

Πmodel(σ(type='Laser')V(color='all')(Printer))

Πmodel(σ(type='Laser')U(color='all')(Printer))

Consider the following schema for products: Product(maker, model, type) PC(model, speed, ram, hd, price) Laptop(model, speed, ram, hd, screen, price) Printer(model, color, type, price) 4. Find those manufacturers that sell Laptops, but not PC’s.

Πmaker(σ(Product.model=Laptop.model)(Product × Laptop)) - Πmaker(σ(Product.model=PC.model)(Product × PC))

Πmaker(Product × Laptop) - Πmaker(Product × PC)

Πmaker(σ(Product.model=Laptop.model)(Product × Laptop))

Πmaker(σ(Product.model=Laptop.model)V (Product.model=Laptop.model)(Product × Laptop × PC))

Consider the following schema for products: Product(maker, model, type) PC(model, speed, ram, hd, price) Laptop(model, speed, ram, hd, screen, price) Printer(model, color, type, price) 5. Find the model number and price of all products (of any type) made by manufacturer B

Πmodel,price(σ(Product.model=Laptop.model)∧(Product.model=PC.model)∧(Product.model=Printer.model)(Product × Laptop × PC × Printer))

Πmodel,price(σ(Product.model=Laptop.model)∧(Product.model=PC.model)(Product × Laptop × PC × Printer))

Πmodel,price(σ(Product.model=Laptop.model)V(Product.model=PC.model)V(Product.model=Printer.model)(Product × Laptop × PC × Printer))

Πmodel(σ(Product.model=Laptop.model)∧(Product.model=PC.model)∧(Product.model=Printer.model)(Product × Laptop × PC × Printer))

Which is perfact syntax for adding column named Salary in employee table

alter table employee add Salary type int;

alter table employee add Column Salary type int;

Insert column Salary into table employee;

Add column Salary in table Employee;

Which is perfact syntax for changing datatype of salary column to numeric in employee table

alter table employee alter column salary type numeric(10) using salary::numeric(10);

alter table employee alter column salary type numeric(10);

alter table employee alter column salary numeric(10) using salary::numeric(10);

alter employee alter column salary type numeric(10) using salary::numeric(10);

Delete whole tuple of Ename deepika from the employee table

Delete from employee where Ename='Deepika';

Delete from employee for Ename='Deepika';

Delete from employee into Ename='Deepika';

How to create the user Jonh with 'abc' password

CREATE USER JHON WITH PASSWORD 'abc';

CREATE USER JHON PASSWORD 'abc';

CREATE USER JHON HAVING PASSWORD 'abc';

CREATE USER JHON WITH 'abc' PASSWORD;

Change the designation of Gaurav from executive to manager in employee table

Update employee set designation='manager' where name ='Gaurav';

Update employee set designation='manager' where designation='executive';

Update employee set designation=manager where name =Gaurav;

Update set designation='manager' where name ='Gaurav';

John have left the job so it need to update the table of employee by removing his name, give proper syntax in SQL

Delete from employee where name='John';

Update from employee where name='John';

Update employee set name=NULL where name='John';

Create a Customer_backup table containing all attribute of Customer table

Create table Customer_backup as select * from Customer

Create table Customer as select * from Customer_backup

Create table Customer_backup as select ALL from Customer

Create table Customer_backup from Customer

Test 2 T1

Authored by Riddhish Thakore

Computers

University

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MULTIPLE CHOICE QUESTION

1 min • 1 pt

What is information about data called?

Hyper data

Tera Data

Meta Data

Super Data

Info Data

MULTIPLE CHOICE QUESTION

1 min • 1 pt

Which of the following is not a Data Model?

Aggregate Model

Network Model

Hierarchical Model

ER model

Relational Model

MULTIPLE CHOICE QUESTION

1 min • 1 pt

The Users who use easy-to-use menu are called____________________.

Naïve User

Database Administrator

Sophesticated User

Application Programmer

Specialised User

MULTIPLE CHOICE QUESTION

1 min • 1 pt

The ________ architecture leads to a performance loss with an increase in the number of users.

two-tier DB

three-tier DB

MULTIPLE CHOICE QUESTION

1 min • 1 pt

A _________ DB architecture is comparatively much easier to maintain as well as build.

two-tier DB

three-tier DB

MULTIPLE CHOICE QUESTION

1 min • 1 pt

______ manager controls the concurrency and atomicity in database system

Authorization manager

Integrity Manager

Transaction Manager

File manager

Buffer Manager

MULTIPLE CHOICE QUESTION

1 min • 1 pt

Multiple users are allowed to access data simaltenously is called ______

Redundancy

Integrety

Atomicity

Concurrency

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Test 2 T1

What is information about data called?

Which of the following is not a Data Model?

The Users who use easy-to-use menu are called____________________.

The ________ architecture leads to a performance loss with an increase in the number of users.

A _________ DB architecture is comparatively much easier to maintain as well as build.

______ manager controls the concurrency and atomicity in database system

Multiple users are allowed to access data simaltenously is called ______

Role based authorities has been assigned can be called as ________

Data contained in the database is both correct and consistent

What is Composite key in DBMS

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