select id from info

id
-----------
1
2
3
5
6
7
8
10
11
12
15

(11 行受影响)

方法一：

select (select max(id)+1 from Info where id<a.id) as beginId,(id-1) as endId
from Info a 
where 
a.id>(select max(id)+1 from Info where id<a.id)

beginId     endId
----------- -----------
4           4
9           9
13         14

(3 行受影响)

方法二：

select beginId,(select min(id)-1 from info where id > beginId) as endId 
from (  
select id+1 as beginId from info where id+1 not in (select id from info) and id < (select max(id) from info)  
) as t

beginId     endId
----------- -----------
4           4
9           9
13          14

(3 行受影响)

说明：

1、查找结果的两列是断号的区间，如果beginId=endId，则表示缺少该号码，否则表示缺少beginId ~ endId；

2、如果号码1不存在，区间1 ~ select min(id)-1 from info 将无法找出