Consecutive Numbers

Desicription

Write a SQL query to find all numbers that appear at least three times consecutively.

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+----+-----+
| 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.

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+-----------------+
| ConsecutiveNums |
+-----------------+
| 1 |
+-----------------+

Solution

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SELECT DISTINCT L1.Num
AS ConsecutiveNums
from Logs L1, Logs L2, Logs L3
WHERE L1.Num = l2.Num AND L1.Num = L3.num AND L1.Id = L2.Id-1 AND L1.Id = L3.Id+1