SELECT [TDPreventivi].*, PREVENTIVI2.* FROM
(SELECT MINDATA.VRDOCID, MINDATA.DATAINIZIO, MAXDATA.DATAULTIMA FROM
(SELECT MIN(VRDATA) AS DATAINIZIO, VRDOCID FROM [dbo].[TDPreventivi]  GROUP BY VRDOCID) MINDATA 
INNER JOIN
(SELECT MAX(VRDATA) AS DATAULTIMA, VRDOCID FROM [dbo].[TDPreventivi]  GROUP BY VRDOCID) MAXDATA  ON MINDATA.VRDOCID = MAXDATA.VRDOCID) TMP
INNER JOIN [dbo].[TDPreventivi] ON TMP.VRDOCID= [dbo].[TDPreventivi].VRDOCID AND TMP.DATANIZIO= [dbo].[TDPreventivi].VRDATA
INNER JOIN [dbo].[TDPreventivi] PREVENTIVI2 ON TMP.VRDOCID= PREVENTIVI2.VRDOCID AND TMP.DATAFINE= PREVENTIVI2.VRDATA