ALTER TABLE OPStockEntryDetails 
ALTER COLUMN itemname NVARCHAR(500); 

ALTER TABLE OPStockUpdatedDetails 
ALTER COLUMN itemname NVARCHAR(500); 

UPDATE OPStockEntryDetails
SET SubId = (
    SELECT id 
    FROM OPStockEntry 
    WHERE OPStockEntry.docno = OPStockEntryDetails.docno
);



UPDATE OPStockUpdatedDetails
SET SubId = (
    SELECT id 
    FROM OPStockEntry 
    WHERE OPStockEntry.docno = OPStockUpdatedDetails.docno
);