#1

SELECT lastname FROM employees ORDER BY lastname;

#2

SELECT DISTINCT lastname FROM employees ORDER BY lastname;

#3

SELECT DISTINCT state FROM customers;

#4

SELECT DISTINCT state, city FROM customers WHERE state IS NOT NULL ORDER BY state , city;

#5

SELECT state, city FROM customers WHERE state IS NOT NULL ORDER BY state , city;

#6

SELECT state FROM customers GROUP BY state;

#7

SELECT DISTINCT state FROM customers;

#8

SELECT DISTINCT state FROM customers ORDER BY state;

#9

SELECT COUNT(DISTINCT state) FROM customers WHERE country = 'USA';

#10

SELECT DISTINCT state FROM customers WHERE state IS NOT NULL LIMIT 5;