查询sql

Question

+--------------+---------------+
| First number | Second number |
+--------------+---------------+
|      1       |       2       |
|      2       |       3       |
|      3       |       4       |
|      4       |       5       |
+--------------+---------------+

所以我在SQL上有这个表。我想得到一个特定数字的所有后代。例如，如果我选择数字2，结果应为：

+--------------+---------------+
|      2       |       3       |
|      3       |       4       |
|      4       |       5       |
+--------------+---------------+

数字不需要按照正确的顺序排列：

+--------------+------------------+
| First number | Following number |
+--------------+------------------+
|      2       |       3          |
|      4       |       5          |
|      3       |       4          |
|      1       |       2          |
+--------------+------------------+

我应该继续获得之前的结果。

我不知道该怎么做，我希望你能帮助我。

Answer 1

您可以使用Recursive CTE

WITH RECURSIVE t
     AS (SELECT *
         FROM   yourtable
         WHERE  "First number" = 2
         UNION ALL
         SELECT a.*
         FROM   yourtable a
                JOIN t b
                  ON b."Second number" = a."First number")
SELECT *
FROM   t 

• Live Demo

Answer 2

这可以通过简单的select语句来实现。

select * from table where "first number" >= 2