there appears to be inconsistency in the way you store "item" across the various tables.

Not sure if this down to your real tables or just the way you have provided example data etc.

short of time at the moment...but one way to try and get everything together would be as follows...

select *

into #temp

from

(

SELECT V1.vouchertype, V1.voucherprefix, V1.voucherno, I.itemname, V1.batchno, V1.quantity

FROM voucher1 AS V1 INNER JOIN items AS I ON V1.item = I.srno

UNION ALL

SELECT vouchertype, voucherprefix, voucherno, item, batchno, qty

FROM voucherPRETSRET

UNION ALL

SELECT 'CASH MEMO' AS vouchertype, voucherprefix, voucherno, itemname, batch, qty

FROM cashmemo

) x

SELECT #temp.*, voucher.dt

FROM #temp LEFT OUTER JOIN voucher ON #temp.vouchertype = voucher.vouchertype

AND #temp.voucherprefix = voucher.voucherprefix

AND #temp.voucherno = voucher.voucherno