SELECT prod_id, prod_price, prod_name FROM products
WHERE vend_id = 1003 AND prod_price <= 10;
SELECT prod_id, prod_price, prod_name FROM products
WHERE vend_id = 1002 OR vend_id = 1003;
SELECT prod_id, prod_price, prod_name FROM products
WHERE vend_id = 1002 OR vend_id = 1003 AND prod_price >= 10; #优先处理AND操作符
SELECT prod_id, prod_price, prod_name FROM products
WHERE (vend_id = 1002 OR vend_id = 1003) AND prod_price >= 10;
SELECT prod_name, prod_price FROM products
WHERE vend_id IN (1002, 1003) #IN操作符和OR操作符功能相同，但优化选用IN
ORDER BY prod_name;
SELECT prod_name, prod_price FROM products
WHERE vend_id NOT IN (1002, 1003) #使用NOT对IN，BETWEEN和EXISTS
ORDER BY prod_name;
