declare dataset in powershell
$dt.TableName = "Me"
$ds = New-Object System.Data.DataSet
$ds.Tables.Add($dt)
$dt2 = New-Object System.Data.Datatable "AnotherTable"
[void]$dt2.Columns.Add("MyColumn")
[void]$dt2.Rows.Add("MyRow")
$ds.Tables.Add($dt2)
$ds.tables["Me"]
$ds.tables["AnotherTable"]