Query That Return Nulls

This is my problem, i have 2 tables: one table that hold data, having id as identity, say table (id, content), the other table have 2 columns: (id, number). The second table number column refer to the id in the first table. i want to build a query that get the data from the first table that correspond to a specific id in the second table, not only this i want to get the previous, the current and the next item.

For example: if table_data, table_info is first and second tables, something that can do it is :

DECLARE @i int

SELECT * FROM table_data WHERE id in (@i -1, @i +1, @i)

The problem here if @i, @i+1 or @i-1 doesn't exist the column will not be returned, i want to get a result similar to

id, content

25 null
26 null
27 #some content#

or

34 #content1#
35 #content2#
36 #content3#

so my problem is that nulls doesn't appear, i thought about using OUTER JOIN, but the problem is that outer join take tables, not (@i -1, @i +1, @i), so if only i can make somehow the outer join use these values, i think it works.

Any help please, and thanks in advance