Use below code to show attachments in sharepoint dataview webpart .
Use this for Single List Item View:
<SharePoint:AttachmentsField ControlMode=”Display” ItemId=”{@ID}” EnableViewState=”true” FieldName=”Attachments” runat=”server”/>
Use this for Multiple List item Vew:
<SharePoint:AttachmentButton ControlMode=”Edit” Enabled=”true” ItemId=”{@ID}” runat=”server” Visible=”false”/><SharePoint:AttachmentsField ControlMode=”Display” ItemId=”{@ID}” EnableViewState=”true” FieldName=”Attachments” runat=”server”/>
