LC-mysql-180(consecutive numbers)

本SQL问题是 #180. Consecutive Numbers

问题

编写SQL，找出至少连续出现三次的所有数字

Tips:

借助一个游标变量@cu来记录重复次数

select distinct(p.Num) as 'ConsecutiveNums' from (
select l.Id,l.Num,
  case 
    when @pre = l.Num THEN @cur := @cur + 1
    when @pre := l.Num THEN @cur := 1
    else  1
  END as c
from Logs as l , (select @pre :=0 ,@cur := 1)t)p 
WHERE p.c = 3

方法2

通过错位连接来筛选(通用性不高)

SELECT DISTINCT L1.Num AS ConsecutiveNums
    FROM Logs L1
    INNER JOIN Logs L2
    ON L1.Id=L2.Id-1
    INNER JOIN Logs L3
    ON L2.Id=L3.Id-1
    WHERE L1.Num=L2.Num AND L1.Num=L3.Num;