Join two tables to get counts different dates - sql

Question

I have a table A with columns:
id, transactiondate, pointsordered
Table B
id,redemptiondate,pointsused
Table C
as
id,joindate
What I want
All data is needed for a date range lets say 2014-01-01 to 2014-02-01 in YYYY-MM-DD
Count of total ids by date ( count of ids from table a)
count of accounts that had the first transaction on this date
total points ordered by date ( sum of points from table a)
count of accounts that redeemed on that date ( count of ids from table b )
countofpointsued on that date ( sum of points from table b)
new customers that joined by date
I understand id is a foreign key for table b and table c but how do i ensure i match the dates ?
for eg if i join by date such as a.transactiondate=b.redemption.date it gives me all the customers that had a transaction on that date and also redeemed on that date.
Where as I want a count of all customers that had transaction on that date and customers that redeemed on that date ( irrespetive of the fact when did they have their transaction)
Here is what I had tried
select count( distinct a.id) as noofcustomers, sum(a.pointsordered), sum(b.pointsused), count(distinct b.id)
from transaction as a join redemption as b on a.transactiondate=b.redemptiondate
where a .transactiondate between '2014-01-01' and '2014-02-01'
group by a.transactiondate,b.redemptiondate

Answer 1

I would first group the data by table and only then join the results by date. You shouldn't use inner join because you may lose data if there is no matching record on one side like no transaction on given date but a redemption. It would help if you'd have a list of dates in that range. If you don't have that you can build one using a CTE.
declare #from date = '2014-01-01'
declare #to date = '2014-02-01'
;
with dates as
(
select #from as [date]
union all
select dateadd(day, [date], 1) as d from dates where [date] < #to
)
, orders as
(
select transactiondate as [date], count(distinct id) as noofcustomers, sum(pointsordered) as pointsordered
from [transaction]
where transactiondate between #from and #to
group by transactiondate
)
, redemptions as
(
select redemptiondate as [date], count(distinct id) as noofcustomers, sum(pointsused) as pointsused
from [redemption]
where redemptiondate between #from and #to
group by redemptiondate
)
, joins as
(
select joindate as [date], count(distinct id) as noofcustomers
from [join]
where joindate between #from and #to
group by joindate
)
, firsts as
(
select transactiondate as [date], count(distinct id) as noofcustomers
from [transaction] t1
where transactiondate between #from and #to
and not exists (
select * from [transaction] t2 where t2.id = t1.id and t2.transactiondate < t1.transactiondate)
group by transactiondate
)
select
d.[date],
isnull(o.noofcustomers,0) as noofcustomersordered,
isnull(o.pointsordered,0) as totalpointsordered,
isnull(f.noofcustomers,0) as noofcustomersfirsttran,
isnull(r.noofcustomers,0) as noofcustomersredeemed,
isnull(r.pointsused,0) as totalpointsredeemed,
isnull(j.noofcustomers,0) as noofcustomersjoined
from dates d
left join orders o on o.[date] = d.[date]
left join redemptions r on r.[date] = d.[date]
left join joins j on j.[date] = d.[date]
left join firsts f on f.[date] = d.[date]
Please note that I didn't run the query so they may be errors, but I think the general idea is clear.