利用函数重载：

' Sub that takes the query and a DGV:
Public Sub ExecuteReaderDataGridView(SQLQuery As String, TargetDataGridView As DataGridView)

    ExecuteReaderDataGridView(SQLQuery, TargetDataGridView, Nothing)

End Sub

' Sub that takes the query and a Form:
Public Sub ExecuteReaderDataGridView(SQLQuery As String, TargetForm As Form)

    ExecuteReaderDataGridView(SQLQuery, Nothing, TargetForm)

End Sub

' Your original Sub:
Public Sub ExecuteReaderDataGridView(SQLQuery As String, TargetDataGridView As DataGridView,TargetForm As Form)

' You'll need to modify your original Sub by adding code
' to determine if TargetDataGridView or TargetForm is Nothing.

End Sub