Given a series of numbers in table(c1), find the missing numbers

Question

Given a series of numbers in table(c1), find the missing numbers. The numbers should be consecutive

c1
--
1
2
3
6
7
8
9
12
14

Expected output:
i
-
4
5
10
11
13

Answer 1

Use generate_series():

select s.i
from (select generate_series(min(c1), max(c2), 1) as i
      from t
     ) s left join
     t
     on s.i = t.c1
where t.c1 is null;