sql - 使用递归公用表表达式从两个表中查找连续编号

Question

我有以下表格:

Actual         Optional
------         --------
4                 3
13                6
20                7
26                14
                  19
                  21
                  27
                  28

我要做的是选择:

1) all the values from "Actual" Table.

2) select values from "Optional" table if they form a consecutive series with "actual" table values

预期的结果是:

Answer
------
4
13
20
26
3    --because it is consecutive to 4 (i.e 3=4-1) 
14   --14=13+1
19   --19=20-1
21   --21=20+1
27   --27=26+1
28   --this is the important case.28 is not consecutive to 26 but 27 
     --is consecutive to 26 and 26,27,28 together form a series.

我使用递归 cte 编写了一个查询，但它永远循环并在递归达到 100 级后失败。
我面临的问题是 27 场比赛与 26、28 场比赛与 27 和 27 与 28.again 28 与 27 ......(永远)

这是我写的查询:

with recurcte as
        (
        select num as one,num as two from actual
        union all
         select opt.num as one,cte.two as two 
         from recurcte cte join optional opt 
         on opt.num+1=cte.one or opt.num-1=cte.one
        )select * from recurcte

Answer 1

;WITH Combined
     AS (SELECT 1 AS Actual, N
         FROM   (VALUES(4),
                       (13),
                       (20),
                       (26)) Actual(N)
         UNION ALL
         SELECT 0 AS Actual, N
         FROM   (VALUES(3),
                       (6),
                       (7),
                       (14),
                       (19),
                       (21),
                       (27),
                       (28)) Optional (N)),
     T1
     AS (SELECT *,
                N - DENSE_RANK() OVER (ORDER BY N) AS Grp
         FROM   Combined),
     T2
     AS (SELECT *,
                MAX(Actual) OVER (PARTITION BY Grp) AS HasActual
         FROM   T1)
SELECT DISTINCT N
FROM   T2
WHERE  HasActual = 1