How To get the First Row Form SQL Group Query? - sql

Question

I have a problem in writing a query.
I'd like to select the first row of each set of rows grouped
My table is Transactions:
userID | Date | StoreID
---------------------------
1 | 8-9-2013 | 10
1 | 9-9-2013 | 10
1 | 10-9-2013| 20
2 | 7-9-2013 | 30
2 | 8-9-2013 | 10
2 | 9-9-2013 | 20
1 | 11-9-2013| 10
2 | 10-9-2013| 20
and I try to this SQL statement:
Select
tr.userID , Min(tr.TransactionDate) FirstDate
From
Transactions tr
Group By
tr.userID
I get this output:
userID | Date
------------------
1 | 8-9-2013
2 | 7-9-2013
But I need the Store ID in every first transaction.
I need it to be like that
userID | Date | StoreID
-------------------------
1 | 8-9-2013 | 10
2 | 7-9-2013 | 30
Please any one can help me

Answer 1

You could use Row_Number().
select UserId, Date, StoreId from (select row_number() over(partition
by UserId order by date) as RowNumber, UserId, Date, StoreId from
Transactions ) as View1 where RowNumber = 1
http://sqlfiddle.com/#!6/e536a/7

Answer 2

You could use a sub-query
SELECT TR1.userID
,TR1.TransactionDate
,TR1.StoreID
FROM Transactions tr1
INNER JOIN
(
Select
tr.userID
,Min(tr.TransactionDate) AS FirstDate
From
Transactions tr
Group By
tr.userID
) SQ
ON TR1.userID = SQ.userID
AND TR1.TransactionDate = SQ.FirstDate

Answer 3

SQL Fiddle
MS SQL Server 2008 Schema Setup:
CREATE TABLE Transactions
([userID] int, [Date] datetime, [StoreID] int)
;
INSERT INTO Transactions
([userID], [Date], [StoreID])
VALUES
(1, '2013-08-09 00:00:00', 10),
(1, '2013-09-09 00:00:00', 10),
(1, '2013-10-09 00:00:00', 20),
(2, '2013-07-09 00:00:00', 30),
(2, '2013-08-09 00:00:00', 10),
(2, '2013-09-09 00:00:00', 20),
(1, '2013-11-09 00:00:00', 10),
(2, '2013-10-09 00:00:00', 20)
;
Query 1:
SELECT
tr.userID , Min(tr.Date) FirstDate , tr2.storeid
FROM
Transactions tr
inner join Transactions tr2 on tr.userid = tr2.userid and
tr2.date = (select top 1 date
from transactions t
where t.userid = tr2.userid
order by date asc)
GROUP BY
tr.userID, tr2.storeid
Results:
| USERID | FIRSTDATE | STOREID |
|--------|-------------------------------|---------|
| 1 | August, 09 2013 00:00:00+0000 | 10 |
| 2 | July, 09 2013 00:00:00+0000 | 30 |

Answer 4

with user_cte (userid,date)
as(Select tr.userID , Min(tr.TransactionDate) FirstDate
From Transactions tr
Group By tr.userID
)
select b.userid,b.date,a.storeId from Transactions a join user_cte b on a.userID=b.userId and a.Date=b.Date

Answer 5

You can do this with a subquery. The basic principle is that the subquery identifies the min date for each one, and the wrapping query picks the row that matches the user and min date, also being able to return the store id.
It would look something like this:
SELECT
t.UserID,
t.Date,
t.StoreId
FROM
Transactions t JOIN
(
SELECT
tr.userID , Min(tr.Date) AS FirstDate
FROM
Transactions tr
GROUP BY
tr.userID
) u ON t.UserId = u.UserId AND t.Date = u.FirstDate
You can check this out yourself in SqlFiddle here.