Add Windows User to local SQL Server with PowerShell

Question

I would like to add an existing local user to the SQL Server as a sysadmin, with PowerShell. fter some research I have the following script so far:

$Username = \         


        

Answer 1

Change

'$Username'

with

"$Username"

Note that in powershell variable aren't expanded in single quote, then '$Username' is take as literal and not for the value of the variable.