1：对指定列进行升序排列
Select * from user order by user_name
2：按照user_id逆序排列
Select * from user order by user_id DESC
2：按照升序排列user_id逆序排列user_age
SELECT * FROM user order by user_id ASC,user_age DESC
3：按照升序排列user_id逆序排列user_age
SELECT * FROM user order by user_age DESC,user_id ASC
注意：前面的条件优先级更高！！
希望能对大家有所帮助。
