ForEach($Database in (Get-ChildItem -FORCE SQLSERVER:SQLlocalhostDEFAULTDatabases))
{
    Write-Host $Database
}

ForEach($Database in (Get-ChildItem -FORCE SQLSERVER:SQLlocalhostDEFAULTDatabases))
{
    Invoke-Sqlcmd -Database $Database -HostName WIN-MAINV98PDFA -Query "select db_name()" -ServerInstance LocalHost
}

Invoke-Sqlcmd -Database Test_1 -HostName WIN-MAINV98PDFA -Query "select db_name()" -ServerInstance LocalHost

Invoke-Sqlcmd -Database [Test_1] -HostName WIN-MAINV98PDFA -Query "select db_name()" -ServerInstance LocalHost