mysql - 使用 MySQL : Display all of the Column_Name in upper case, 按字母顺序排序，不重复

Question

我已经完成了这个问题，除了我需要我的查询不显示重复项。我该怎么做:

SELECT UPPER(surname) 
FROM customers
ORDER BY surname;

Answer 1

SELECT DISTINCT UPPER(surname) 
FROM customers
ORDER BY surname;