Joining 2 fields in a select statement

To trim spaces, you can make use of LTRIM() and RTRIM() functions
Check this complete article on trimming by my favorite, Pinal Dave.
SQL SERVER – 2008 – TRIM() Function – User Defined Function[^]

Example:
For individual field trimming-

SELECT AIDNO,
(LTRIM(RTRIM(ALOANUMBER))) + LTRIM(RTRIM(AIDNO))) AS LOAM
FROM VLOANS

For the concatenated result trimming-

SELECT AIDNO,
LTRIM(RTRIM((ALOANUMBER + AIDNO))) AS LOAM
FROM VLOANS

Hope, it helps :)

Note: For SQL Server 2012/2014, there is a function exists, TRIM() which does the same thing instead of using two functions.