refactor 614

Author: fishercoder1534

Diff for: database/_614.sql

@@ -1,31 +1,3 @@
---614. Second Degree Follower
---In facebook, there is a follow table with two columns: followee, follower.
---
---Please write a sql query to get the amount of each follower’s follower if he/she has one.
---
---For example:
---
---+-------------+------------+
---| followee    | follower   |
---+-------------+------------+
---|     A       |     B      |
---|     B       |     C      |
---|     B       |     D      |
---|     D       |     E      |
---+-------------+------------+
---should output:
---+-------------+------------+
---| follower    | num        |
---+-------------+------------+
---|     B       |  2         |
---|     D       |  1         |
---+-------------+------------+
---Explaination:
---Both B and D exist in the follower list, when as a followee, B's follower is C and D, and D's follower is E. A does not exist in follower list.
---Note:
---Followee would not follow himself/herself in all cases.
---Please display the result in follower's alphabet order.
-
 select f1.follower, count(distinct f2.follower) as num
 from follow f1
 inner join follow f2 on f1.follower = f2.followee