If you don't have enough qualification, the result is a syntax error ("Type 'OleDbCommand' is not defined") because the Imports namespace qualification System.Data doesn't provide enough information to find the object OleDbCommand.
~~~~~~~~~~~~~~~~~~~~~~~~~
Imports System.Data
Public Class Form1
Inherits System.Windows.Forms.Form
Private Sub Form1_Load( ...
Dim Test As OleDbCommand
End Sub
End Class
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