Write the following queries in SQL based on the following schema:COP5725 - Spring 2011• Product(maker, model, type)• PC(model, speed, ram, hd, price)• Laptop(model, speed, ram, hd, screen, price)• Printer(model, color, type, price)a) Give the manufacturer and speed of laptops with a hard disk of at least 30 gigabytesSELECT R. maker AS manufacturer, L.speed AS gigahertzFROM Product R, Laptop LWHERE L. hd>= 30AND R. model = L. modelAND R. type= ‘laptop’;b) Find the model number and price of all products (of any type) made by manufacturer 'B'SELECT R. model, P. price FROM Product R, PC PWHERE R. maker= 'B‘ AND R. model = P. modelUNIONSELECT R. model, L. price, FROM Product R, Laptop LWHERE R. maker= 'B‘ AND R. model = L. modelUNIONSELECT R. model, T. price FROM Product R, Printer TWHERE R. maker= 'B’ AND R. model = T. model ;c) Find those manufacturers that sell Laptops, but no PC'sSELECT R. makerFROM Product R, Laptop LWHERE R. model = L. model and R. Type= ‘Laptop’EXCEPTSELECT R. makerFROM Product R, PC PWHERE R. model = P. model and R. Type= ‘PC’ ;d) Find those hard-disk sizes that occur in two or more PC'sSELECT DISTINCT P1.hdFROM PC P1, PC P2WHERE P1.hd = P2.hd AND P1.model > P2.model ;Alternate SELECT DISTINCT P. hdFROM PC PGROUP BY P. hdHAVING COUNT(*) >= 2 ;