Can you try dividing by 1.00 to convert the integer into decimal?

select
    AVG(HalfTimeAwayGoals/1.00) as average 
from
    testtable 
where
    AwayTeam = 'TeamA'

I used the /1.00 OR /1.0000 trick on various databases to do the job. Unfortunately, I don't have access MS-SQL to try it. The division of integer by 1.00 will change the integer to decimal.

SELECT AVG(integerfield/1.00) FROM table

cast(avg(cast(LoginCount as decimal(12,2))) as decimal(12,2))

In MySQL

SELECT AVG(integerfield) FROM table

gives me 4 decimal points.

If I do

SELECT AVG(integerfield/1.00) FROM table

I get 8 decimal points.

select 
    AVG(CAST(HalfTimeAwayGoals as decimal(4,2))) 
from 
    testtable 
where 
    AwayTeam = 'TeamA'

If the field HalfTimeAwayGoals is an integer, then the avg function does an integer average. That is, the result is 0 or 1, but cannot be in between.

The solution is to convert the value to a number. I often do this just by multiplying by 1.0:

select CAST(AVG(HalfTimeAwayGoals * 1.0) as decimal(4, 2)) 
from testtable 
where AwayTeam = 'TeamA';

Note that if you do the conversion to a decimal before the average, the result will not necessary have a scale of 4 and a precision of 2.