题目5：MySQL----------Consecutive Numbers

最新推荐文章于 2024-09-08 13:36:12 发布

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#MySQL #database #Consecutive Numbers

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本文提供了一个SQL查询示例，用于找出在给定日志表中连续出现三次及以上的数字。通过使用窗口函数和变量，实现对连续重复数字的筛选。

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.

题目解答

# Write your MySQL query statement below
select distinct Num from (
    select
        Num,
        case
            when @prevNum = Num then @count := @count + 1
            when (@prevNum := Num) is not null then @count := 1
        end n
    from Logs, (select @prevNum := NULL) r
    order by Id
) a where n >= 3