Extract data from System.Data.DataRow in powershell

Assuming the column name is GroupID

$sql = "SELECT [GroupID] FROM theTable"
$table = Invoke-SQLCmd -Query $sql -ServerInstance $sqlServerInstance -Database $database -OutputAs DataRows

foreach($user_info in $table)
{
    $user_info.GroupID
}

or

foreach($user_info in $table.GroupID)
{
    $user_info
}

You can also use ItemArray. Prints the entire row, while Item(index) prints the values from the indexed cell.

Item is a parameterized property, not a list you can index into:

foreach($row in $table)
{
    $row.Item("GroupID")
}

or (assuming that "GroupID" is the first column):

foreach($row in $table)
{
    $row.Item(0)
}