<p>I am porting some queries from Access to T-SQL and those who wrote the queries used the Avg aggregate function on datetime columns.  This is not supported in T-SQL and I can understand why - it doesn't make sense.  What is getting averaged?</p>

<p>So I was about to start reverse engineering what Access does when it aggregates datetime using Avg, but thought I would throw the question out here first.</p>

I'd imagine that Access is averaging the numeric representation of the dates.  You could do similar in T-SQL with the following...
```
```
select AverageDate = cast(avg(cast(MyDateColumn as decimal(20, 10))) as datetime)
from    MyTable
```
```