Want The Total Balance Of Users..

create table users ([uid] INT PRIMARY KEY IDENTITY(1,1), name nvarchar(100))
create table balance(bid INT IDENTITY(1,1) PRIMARY KEY, [uid] INT, dr FLOAT, cr FLOAT, FOREIGN KEY ([uid]) REFERENCES users([uid]))
GO
insert users ([Name]) values ('Haider'),('Ali')
GO
insert balance ([uid],[cr],[dr]) values (1,1000,null),(1,null,3000),(1,1000,null),(2,2000,null),(2,1000,null),(2,null,500)
GO
--select * from users
select b.uid, sum(Isnull(dr,0)-ISNULL(cr,0)) as Balance 
from balance b join users u on b.uid=u.uid
Group by b.uid
 


drop table  balance, users