สอบถามเรื่องการตัด row ที่ซ้ำกันออกหลังจาก query มาแล้ว เขียนอย่างไรคะ

select   
	distinct pohd.DocuNo,
	pohd.RefDocuNo,
	pohd.VATAmnt,  
	pohd.SumGoodAmnt,
	pohd.CancelCause,
	pohd.CancelFlag,
	pohd.BillDiscFormula,   
	pohd.BillDiscAmnt,   
	pohd.BillAftrDiscAmnt,   
	pohd.NetAmnt NetAmnt,   
	(pohd.docustatus)docustatus,
	(pohd.onhold)onhold ,
	(pohd.cancelflag)cancelflag,
	EMVendor.VendorName ,
	EMDept.Deptcode,
	pohd.DocuStatus,
	
	SUM(poinvhd.TotabaseAmnt) as TotaBaseAmnt,
	(pohd.BillAftrDiscAmnt-poinvhd.TotaBaseAmnt) as Cancel,
	
	CONVERT( VARCHAR( 20 ), pohd.DocuDate, 103 ) as DocuDate ,
	CONVERT( VARCHAR( 20 ), pohd.ShipDate, 103 ) as ShipDate
 	FROM  	POHD pohd 
	inner join EMVendor EMVendor on pohd.VendorID = EMVendor.VendorID
	inner join emdept emdept on pohd.deptid=emdept.deptid
	inner join poinvhd on poinvhd.pono=pohd.docuno

	where  pohd.docudate between  '2013/01/01' and '2013/03/01' 
	 and pohd.docutype='305' and pohd.MultiCurr = 'N'  and pohd.cancelflag='y'
	GROUP BY pohd.DocuNo,
	pohd.VATAmnt,  
	pohd.RefDocuNo,
pohd.SumGoodAmnt,
pohd.CancelCause,
pohd.CancelFlag,
pohd.BillDiscFormula,   
pohd.BillDiscAmnt,   
pohd.BillAftrDiscAmnt,   
pohd.NetAmnt,   
pohd.docustatus,
pohd.onhold ,
pohd.cancelflag,
EMVendor.VendorName ,
EMDept.Deptcode,
pohd.DocuStatus,
pohd.DocuDate,
pohd.ShipDate,
poinvhd.TotabaseAmnt,

	
	 order by pohd.docuno" ;