Add an existing SQL user to a role for a specific database

Add-SQLDBUserToRole.ps1

Write-Output "Loaded Add-SQLDBUserToRole function"
Function Add-SQLDBUserToRole {
  Param (
    [string] $server, 
    [String] $Database , 
    [string]$User, 
    [string]$Role
  )
  $Svr = New-Object ('Microsoft.SqlServer.Management.Smo.Server') $server
  $db = $svr.Databases[$Database]
  if($db -eq $null) {
    Write-Host " $Database is not a valid database on $Server"
    Write-Host " Databases on $Server are :"
    $svr.Databases| Select-Object name
    break
  }
  #Check Role exists on Database
  $Rol = $db.Roles[$Role]
  if($Rol -eq $null) {
    Write-Host "$Role is not a valid Role on $Database on $Server"
    Write-Host "Roles on $Database are:"
    $db.roles | Select-Object name
    break
  }
  if(!($svr.Logins.Contains($User))) {
    Write-Host "$User not a login on $server create it first"
    break
  }
  if (!($db.Users.Contains($User))) {
    # Add user to database
    $usr = New-Object ('Microsoft.SqlServer.Management.Smo.User') ($db, $User)
    $usr.Login = $User
    $usr.Create()
    #Add User to the Role
    $Rol = $db.Roles[$Role]
    $Rol.AddMember($User)
    Write-Host "$User was not a login on $Database on $server"
    Write-Host "$User added to $Database on $Server and $Role Role"
  }
  else {
    #Add User to the Role
    $Rol = $db.Roles[$Role]
    $Rol.AddMember($User)
    Write-Host "$User added to $Role Role in $Database on $Server"
  }
}