Q 5

I) 1.How shall we use the Aggregate function in the where clause?

2.What is Timestamps column?

3.Can I update a view?

4.What is Defaults Limitations?

5.What are the types of Constraints?

II) The database scheme consists of four relations:

Product(maker, model, type)
PC(code, model, speed, ram, hd, cd, price)
Laptop(code, model, speed, ram, hd, screen, price)
Printer(code, model, color, type, price)

The relation "Product" shows the maker, model number, and type (pc, laptop, or printer). It is assumed that model numbers are unique for all the makers and product types. For each model number specifying pc in the relation "PC", its listed speed (of the processor in MGz), total RAM (in MGb), hd capacity (in Gb), CD ROM speed (for example, '4x'), and the price. The relation "Laptop" is similar to that one of PCs except for the CD ROM speed which is replaced by screen size (in inches). For each printer model in the relation "Printer" it is pointed whether the printer is color or not (color attribute is 'y' for color printers; otherwise it is 'n'), printer type (laser, jet, or matrix), and the price.

  1. Find maker, price who produce the costly laptop.

  2. Delete all the jet printers

3. Find the maker who produces printer with minimum hd (price)

4. Update the speed as 750 for the laptops which has the lowest price

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