Concatenate Properties from a System.Data.DataRow object in powershell

I have stored the results of an sql server query in a variable named $TESTER using the Invoke-Sqlcmd cmdlet.

I want to take the fields from each row (i.e. name, address etc) and concatenate them into a seperate string parameter named $STR

something similar to the below

$TESTER | Select-Object | ForEach-Object {$STR = $.name + $.address + $_.postcode}

Any ideas?