0) You don't need the
if
clause:
SELECT a.Brand,
a.model,
a.serialno,
a.Status,
b.GroupName
FROM status a
INNER JOIN Group b ON a.GroupId = b.GroupId
WHERE a.Status = 'Active'
1) Your table names are the same as some of your column names. That's confusing.
2) Your aliases are not real indicative of which table they represent. I suggest using the first letter of the name of the table instead.