I have two tables:
tbl_Invoice

tbl_payment

When I pass client_Id = 5 then the Desired Output should be:
PSUM IPRICE Amt_Type
----------- -------------- ----------------
100.00 100.00 USD
0.00 1000.00 GBP
Where
PSUM is Sum of total Payments
IPRICE is Sum of total Price of Invoices
What I have tried is:
Select SUM(P.Amt) as PSUM, SUM(I.Total_price) as IPRICE, I.Amt_Type from
[tbl_payment] P left join [tbl_Invoice] I on P.invoice_Id = I.invoice_Id
WHERE P.client_id = @Client_Id and I.client_id = @Client_Id
group by I.Amt_Type
The following appears to be working:
See SQL Fiddle with Demo
Result: