SQL SUM GROUP BY two tables

Question

I\'m having difficulty writing an SQL query that will correctly group account_no together and subtracting an amount.

Firstly I wrote this query which updates everyth

Answer 1

Are you looking how to join tables and sum using group by?

First query;

UPDATE: I think your Account table has 1:many relationship with Transaction table, so, you should get the sum from transaction table and then join with Account. Ideally, you need a left join as below.

select a.account_no, 
       a.balance, 
       isnull(x.amount,0) amount, 
       (a.balance + isnull(x.amount,0)) correctAmount
from account a left join (
           select t.account_no, sum(t.amount) amount
           from transactions t
           group by t.account_no ) x
   on a.account_no = x.account_no

SQL-FIDDLE-DEMO (thanks @Josien for tables and data)