COMPSCI 280
Computer
Science
Exercise 13 Solution
Exercise 1: List the foods and their prices. Add the message “expensive” or “Good deal” to
the foods that cost more than $2. List the foods in alphabetical order.
 The rows of data are divided into two groups
o Price > $2 => “Expensive”
o Price <= $2 => “Good deal”
Answer:
select description, price, 'expensive' as message
from L_FOODS
where price > 2
UNION ALL
select description, price, 'Good deal'
from L_FOODS
where price <= 2 Or price is null
Order by description;
Exercise 2:
Consider the table1:
ITEM
SAMSONITE SUITCASE
RENT FOR APRIL
OPERA TICKET
LUNCH
DEBT REPAID BY JIM
CAR REPAIR
HAIRCUT
BIRTHDAY GIFT FROM MOM
COSTΞΞ
-248.13
700
-145
-15.62
20
-622.98
-22
200
and Table2:
ITEM
BIRTHDAY GIFT FROM MOM
CAR REPAIR
DEBT REPAID BY JIM
HAIRCUT
LUNCH
OPERA TICKET
RENT FOR APRIL
SAMSONITE SUITCASE
debits
null
-622.98
null
-22
-15.62
-145
null
-248.13
credits
200
null
20
null
null
null
700
null
Convert the table1 into the table2
Answer:
select item, null as debits, cost as credits
from finances
where cost > 0
union all
select item, cost, null
from finances
where cost < 0 or cost is null
order by item;
1
Exercise 3: Increase the price of all foods costing more than $2 by 5%. Increase the price
of all other foods by 10%. Ignore the existing price_increase column.
menu_item
1
2
3
4
5
6
7
8
9
10
description
Fresh Salad
Soup Of The Day
Sandwich
Grilled Steak
Hamburger
Broccoli
French Fries
Soda
Coffee
Dessert
price
2
1.5
3.5
6
2.5
1
1.5
1.25
0.85
3
new_price
2.200000
1.650000
3.675000
6.300000
2.625000
1.100000
1.650000
1.375000
0.935000
3.150000
Answer:
select menu_item,
description,
price + (price * .05) as new_price
from l_foods
where price > 2.00
or price is null
union all
select menu_item,
description,
price + (price * .10)
from l_foods
where price <= 2.00
order by menu_item;
2