How to find missing sequence number which is minimum

Question

I have one table which has sequence number.

I want to find the missing sequence number which is minimum out of missing numbers.

For eg.,

Seq No: 1,2,3,5,7,9 ==> Expected result: 4
Seq No: 1,2,3,4,5,6,7,9,15 ==> Expected result: 8

Answer 1

You can try with row_number()

with cte as
(
select seq,seq-row_number() over(order by seq) as diff
from tablename
)
select * from cte where diff<>0 and diff in (select min(diff) from cte where diff<>0)