ORDER BY a 
ORDER BY a,b
ORDER BY a, b, c 
ORDER BY a DESC, b DESC, c DESC 

WHERE a = const ORDER BY b, c 
WHERE a = const AND b = const ORDER BY c 
WHERE a = const ORDER BY b, c 
WHERE a = const AND b > const ORDER BY b, c 

ORDER BY a ASC, b DESC, c DESC//排序方向不一致
WHERE g = const ORDER BY b, c // 字段g不是索引一部分
WHERE a = const ORDER BY c //没有使用字段b 
WHERE a = const ORDER BY a, d // 字段d不是索引的一部分 

mysql> SELECT <cols> FROM profiles INNER JOIN (
-> SELECT <primary key cols> FROM profiles
-> WHERE x.sex='M' ORDER BY rating LIMIT 100000, 10
-> ) AS x USING(<primary key cols>);