>>I was trying the group by clause in both the select statements
>>Rajesh
>
>The GROUP BY clause in each part of UNION Selects will group only the part where it is used. What you trying to do? Can you post some example data and desired result?

I suggest clients provide that for every change request. Simple data like ...

Invoice 1
Line item 1 qty 2 price $1 extended $2
Line item 2 qty 4 price $2 extended $8
total $10

You can eyeball this and know the invoice is correct.