mysql - mysql选择值按顺序排列的记录

Question

如何选择 ID1 值按顺序（两个或多个）与 TOWN 匹配的记录

我的桌子

TOWN    ID1
town1   1
town1   2
town1   4 
town2   1
town2   5 
town2   8 
town3   1 
town3   2 
town3   3 

要求的结果

TOWN    ID1
town1   1
town1   2
town3   1 
town3   2 
town3   3 

sql小提琴

http://sqlfiddle.com/#!2/b409f/26

Answer 1

您可以使用EXISTS子句检查序列中的下一个值。此代码将仅匹配长度 >= 2 的“序列”，这似乎是您从示例中想要的。

SELECT * 
  FROM Table1 a 
 WHERE EXISTS (SELECT * 
                 FROM Table1 b 
                WHERE b.TOWN=a.TOWN 
                  AND b.ID1 IN (a.ID1 - 1, a.ID1 + 1))
 ORDER BY TOWN, ID1

Answer 2

如果您的问题是“给我所有与城镇相邻id1的行”，那么只需：

select distinct t1.*
from Table1 t1
join Table1 t2 on t2.town = t1.town and ABS(t1.ID1 - t2.ID1) = 1
order by 1, 2

请参阅SQLFiddle。

---

要在另一列上也匹配，请将条件添加到联接中，例如：

select distinct t1.*
from Table1 t1
join Table1 t2
  on t2.town = t1.town
  and t2.state = t1.state
  and ABS(t1.ID1 - t2.ID1) = 1
order by 1, 2