DATE FUNCTION

i have just started working on SQL and i am trying to solve this puzzle maybe smoe one could do it.. i have to make a query such that
it will take all the transactions throughout the day sort them with the accnt number and then give total amount in the transaction, also the total amount should be > 10000 if some one can try and locate the problem with hte logic i would appreciate it..

just for instance what i did was i tried using the convert in group by and then sum(deposit) this doesnt work.. i am really confused please help.

i have written this query:

declare @datelastweek as datetime
declare @yesterday as datetime
declare @date as datetime
set @Date = Convert(varchar,GetDate() - 1,1)
SET @datelastweek = DATEADD(Day, 1, (DATEADD(Week, -1, @Date)))
SET @yesterday = dateadd(day,1,(dateadd(day,-1,@date)))


select accountno, sum(amount), convert (varchar, TransactionTime -1,1)
from deposit tb join transaction t on tb.id=t.id
where TxnTime between @datelastweek and @date
group by DATEADD(d,DATEDIFF(d,0,TxnTime),0),t.Accountno, txntime
having sum(tb.amount)>10000

Rahul