我想让month（）函数返回值为'jan'，feb等

I want output of Mysql Month() function as 'Jan',Feb etc.

SELECT MONTHNAME(curdate());

Doc

or if you only need the first 3 letters

SELECT substr(MONTHNAME(curdate()), 1, 3);

You could use date_format

select DATE_FORMAT("2017-06-15", "%b");