Description:
Write a SQL query to find all numbers that appear at least three times consecutively.
±—±----+
| Id | Num |
±—±----+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 1 |
| 6 | 2 |
| 7 | 2 |
±—±----+
For example, given the above Logs table, 1 is the only number that appears consecutively for at least three times.
±----------------+
| ConsecutiveNums |
±----------------+
| 1 |
±----------------+
Solution:
選出三個 l1 l2 l3. 用來表示三個連續且相等的元素
# Write your MySQL query statement below
select distinct l1.Num as ConsecutiveNums
from
Logs as l1,
Logs as l2,
Logs as l3
where
l1.Id = l2.Id - 1
and l2.Id = l3.Id - 1
and l1.Num = l2.Num
and l2.Num = l3.Num