Column names can also be used within conditional expressions.
SELECT hno, roomtype, price
FROM room
WHERE price*7 < 500
AND roomtype = 'single'
The query only selects hotels where the weekly price of a single room is less than $ 500.00. The weekly price is not displayed, because this was not required in the output list.
Find all hotels where the weekly price is less than $ 500.00 after a price increase of 5 percent:
SELECT hno, roomtype, price
FROM room
WHERE (price*1.05)*7 < 500
AND roomtype = 'single'
The price for two days can be calculated in the following way:
SELECT hno, roomtype, price*2 two_days
FROM room
WHERE roomtype = 'single'
or
SELECT hno, roomtype, price+price two_days
FROM room
WHERE roomtype = 'single'
Show the prices for one day, two days and a week:
SELECT hno, roomtype, price, price+price two_days, price*7 week
FROM room
WHERE roomtype = 'single'
Show the customers with positive accounts and add the constant 'CREDIT_BALANCE':
SELECT name, account, 'CREDIT_BALANCE' comment
FROM customer
WHERE account > 0
Let the sum of the positive accounts be $ 9774.00. Show the percentage portions of all customers (with positive accounts), rounded to the second place to the right of the decimal point, and sorted in descending order:
SELECT name, account, fixed (account/9774.00*100,5,2) percentage
FROM customer
WHERE account > 0
ORDER BY 3 DESC
