Leetcode 180. 连续出现的数字

https://leetcode-cn.com/problems/consecutive-numbers/

select 
 distinct d.ConsecutiveNums
from 
(
    SELECT c.bianHao,c.num ConsecutiveNums
    FROM 
    (
        SELECT
         a.Num
        ,(SELECT @num   := IFNULL((CASE WHEN @preNum=a.Num then @num+1 else 1 end),1))bianHao
        ,(SELECT @preNum:= (CASE WHEN Id=-1 then NULL else a.Num end))     preNum
        FROM (
            SELECT * FROM Logs
        ) a, (SELECT @num:=1,@preNum:=NULL) b
    )c 
    group by c.bianHao,c.num
    having c.bianHao>=3
)d