Usage of Group By and Order By in Mysql

Question

The table from which I have tried to read

Here I am trying to read the rows which has the latest TransactionDate and grouped by StackHistoryID.

So I thought of using "order by TransactionDate desc" first then the latest row will be top and if I use group by after that it will give what i have wanted. But I figured that, We can not use groupby after using orderby. So I struck here, Is there any way to get what I have wanted using a single query.

UPDATE:

select ID, Max(TransactionDate) from Stacks group by StackHistoryID

But the ID for the first row in this output should be 9.

Answer 1

See SQLFiddle

use MAX()

select StackHistoryID, Max(TransactionDate)
from Stacks
group by StackHistoryID;

And simple query with ID, use MAX; (if the ID is incremental, ie higher id can not have lower date):

select Max(ID),StackHistoryID, Max(TransactionDate)
from Stacks
group by StackHistoryID;

And if your ID is not incremental together with date, ie you could have a higher ID with lower date... Then you could do something like:

select alls.ID, s.StackHistoryID, s.TransactionDate
from
(
  select StackHistoryID as StackHistoryID, 
         Max(TransactionDate) as TransactionDate
  from stacks
  group by StackHistoryID desc 
) s, Stacks alls
where
  alls.StackHistoryID = s.StackHistoryID
  and
  alls.TransactionDate = s.TransactionDate
order by StackHistoryID
;

See SQLFiddle

Answer 2

If you want all data for stackhistoryid with transactiondate sorted. then go for.

select * from stacks order by StackHistoryID, TransactionDate desc;

If you need only latest date go for result specified by @MrSimpleMind