Update record for the last week - sql

Question

I'm building a report that needs to show how many users were upgraded from account status 1 to account status 2 each hour for the last week (and delete hours where the upgrades = 0). My table has an updated date, however it isn't certain that the account status is the item being updated (it could be contact information etc).
The basic table config that I'm working with is below. There are other columns but they aren't needed for my query.
account_id, account_status, updated_date.
My initial idea was to first filter and look at the data for the current week, then find if they were at account_status = 1 and later account_status = 2.
What's the best way to tackle this?

Answer 1

This is the kind of thing that you would use a SELF JOIN for. It's tough to say exactly how to do this without getting any kind of example data, but hopefully you can build off of this at least. There are a lot of tutorials on how to write a successful self join, so I'd refer to those if you're having difficulties.
select a.account_id
from tableName a, tableName b
where a.account_id= b.account_id
and
(a.DateModified > 'YYYY-MM-DD' and a.account_status = 1)
and
(b.DateModified < 'YYYY-MM-DD' and b.account_status= 2)

Answer 2

Maybe you could try to rank all the updates older than an update, with a status of 2 for an account by the timestamp descending. Check if such an entry with status 1 and rank 1 exists, to know that the respective younger update did change the status from 1 to 2.
SELECT *
FROM elbat t1
WHERE t1.account_status = 2
AND EXISTS (SELECT *
FROM (SELECT rank() OVER (ORDER BY t2.updated_date DESC) r,
t2.account_status
FROM elbat t2
WHERE t2.account_id = t1.account_id
AND t2.updated_date <= t1.updated_date) x
WHERE x.account_status = 1
AND x.r = 1);
Then, to get the hours you, could create a table variable and fill it with the hours worth a week (unless you already have a suitable calender/time table). Then INNER JOIN that table (variable) to the result from above. Since it's an INNER JOIN hours where no status update exists won't be in the result.
DECLARE #current_time datetime = getdate();
DECLARE #current_hour datetime = dateadd(hour,
datepart(hour,
#current_time),
convert(datetime,
convert(date,
#current_time)));
DECLARE #hours
TABLE (hour datetime);
DECLARE #interval_size integer = 7 * 24;
WHILE #interval_size > 0
BEGIN
INSERT INTO #hours
(hour)
VALUES (dateadd(hour,
-1 * #interval_size,
#current_hour));
SET #interval_size = #interval_size - 1;
END;
SELECT *
FROM #hours h
INNER JOIN (SELECT *
FROM elbat t1
WHERE t1.account_status = 2
AND EXISTS (SELECT *
FROM (SELECT rank() OVER (ORDER BY t2.updated_date DESC) r,
t2.account_status
FROM elbat t2
WHERE t2.account_id = t1.account_id
AND t2.updated_date <= t1.updated_date) x
WHERE x.account_status = 1
AND x.r = 1)) y
ON convert(date,
y.updated_date) = h.convert(date,
h.hour)
AND datepart(hour,
y.updated_date) = datepart(hour,
h.hour);
If you use this often and/or performance is important, you might consider to introduce persistent, computed and indexed columns for the convert(...) and datepart(...) expressions and use them in the query instead. Indexing the calender/time table and the columns used in the subqueries is also worth a consideration.
(Disclaimer: Since you didn't provide DDL of the table nor any sample data this is totally untested.)