1,
SELECT `customerNumber`, SUM(`amount`) as `totalAmount`
FROM `payments`
WHERE `customerNumber` < 100 or `customerNumber` > 150
GROUP BY `customerNumber`;

2,
SELECT `productCode`, `productName`, `buyPrice`, `MSRP`
FROM `products`
WHERE (`MSRP` BETWEEN 50 and 100) and (`productName` LIKE '%00' or `productName` LIKE '%10' or `productName` LIKE '%12')
ORDER BY `buyPrice`
LIMIT 2;

3,
ALTER TABLE `employees`
ADD `salary` DECIMAL(15) NOT NULL AFTER `jobTitle`;

INSERT INTO `employees` (`employeeNumber`, `lastName`, `firstName`, `extension`, `email`, `officeCode`, `reportsTo`, `jobTitle`, `salary`) VALUES ('123456', 'Nguyen', 'Quan', 'x5800', 'minhquan@gmail.com', '1', '1401', 'bonjour', '100000000000');

UPDATE `customers`
SET `salesRepEmployeeNumber` = '123456'
WHERE `salesRepEmployeeNumber` = '1401' or `salesRepEmployeeNumber` = '1501'

4,
SELECT `orderNumber`, `requiredDate`, `orderDate`, IF(`comments` is NULL, '', SUBSTR(`comments`, 1, 10)) AS `shortComments`
FROM `orders`
WHERE (MONTH(`orderDate`) BETWEEN 7 and 8) and (DATEDIFF(`requiredDate`, `orderDate`) >= 5)

5,
ALTER TABLE `offices`
ADD `manager` INT(11) AFTER `phone`;

ALTER TABLE `offices`
ADD CONSTRAINT `relation_manager`
FOREIGN KEY (`manager`) REFERENCES `employees`(`employeeNumber`)
ON DELETE RESTRICT ON UPDATE CASCADE;

UPDATE `offices`
SET `manager` = '1002';

ALTER TABLE `offices`
CHANGE `manager` `manager` INT(11) NOT NULL;