Exercise TABLE PC ( );
model CHAR(30), speed DECIMAL(4,2), ram INTEGER, hd INTEGER,
price DECIMAL(7,2)
Exercise TABLE Laptop ( );
model CHAR(30), speed DECIMAL(4,2), ram INTEGER, hd INTEGER,
screen DECIMAL(3,1), price DECIMAL(7,2)
Exercise TABLE Printer (
model CHAR(30), color BOOLEAN,
type CHAR (10), price DECIMAL(7,2)
);
Exercise TABLE Printer DROP color;
Exercise TABLE Laptop ADD od CHAR (10)
Exercise TABLE Classes ( class CHAR(20), type CHAR(5), country CHAR(20), numGuns INTEGER, bore DECIMAL(3,1), displacement INTEGER
);
Exercise TABLE Ships ( name CHAR(30), class CHAR(20),
launched INTEGER
DEFAULT ‘none’;
);
Exercise TABLE Battles ( );
name CHAR(30), date DATE
Exercise TABLE Outcomes ( );
ship CHAR(30), battle CHAR(30), result CHAR(10)
Exercise TABLE Classes DROP bore;
Exercise TABLE Ships ADD yard CHAR(30);
Exercise
R1 := σspeed ≥ (PC) R2 := πmodel(R1)
model
1005 1006 1013 Exercise R1 := σhd ≥ 100 (Laptop)
R2 := Product (R1) R3 := πmaker (R2)
maker E A B R4 := πmodel,price (R1)
F G R5 := πmodel,price (R2) R6: = πmodel,price (R3) R7 := R4 R5 R6
Exercise R1 := σmaker=B (Product PC)
R2 := σmaker=B (Product Laptop) R3 := σmaker=B (Product Printer)
model 1004 1005 price 649 630 1006 2007
1049 1429 Exercise
R1 := σcolor = true AND type = laser (Printer) R2 := πmodel (R1)
model Exercise
3003 3007
R1 := σtype=laptop (Product) R2 := σtype=PC(Product) R3 := πmaker(R1)
R4 := πmaker(R2) R5 := R3 – R4
maker Exercise R1 := ρPC1(PC)
F
G
R2 := ρPC2(PC)
R3 := R1 = AND <> R2
R4 := πhd(R3)