Latest Number of Consecutive Days ("Current Streak")

Question

Using SQL Server (On Azure)
I am trying to figure out how to get the latest number of consecutive days in an SQL query.
I have a habit tracking app in which I keep track of best streaks, originally I was storing this "Streak" value as it's own column in the Habit table and changing it directly. This of course led to incorrect syncing and accuracy issues. I realize
the best way to do it is to calculate from existing data.
I simplified the 2 tables as listed below:
Habit
id (the habit id)
Name (the name of the habit)
Target (the target number of entries required to be considered completed)
HabitEntry
id (the habit entry id)
HabitID (the corresponding habit id)
EntryDate (the date and time of the entry)
Looking to get a query that looks something like this:
SELECT habit.id, habit.Name, (*subquery*) as 'CurrentStreak' from habit join habitentry on habit.id = habitentry.habitid
And outputs something like this:
1, 'Exercise Daily', 7
If the habit's target is 2, there must be 2 entries within that date to be considered completed and to add to the streak.
Not sure if this complicates things, but days are measured from 3:00am to 3:00am, any help is greatly appreciated.

Answer 1

Figured I'd throw this in just for the fun of it. :)
IF OBJECT_ID('tempdb..#Habbit') IS NOT NULL DROP TABLE #Habbit
CREATE TABLE #Habbit (
ID INT PRIMARY KEY,
Name VARCHAR(255),
[Target] INT
INSERT #Habbit (ID,Name,Target) VALUES
(1,'Three Day Thing', 3),
(2,'Four Day Thing', 4),
(3,'Five Day Thing', 5)
--=============================================
IF OBJECT_ID('tempdb..#HabitEntry') IS NOT NULL DROP TABLE #HabitEntry
CREATE TABLE #HabitEntry (
UserID INT,
HabbitID INT,
EntryDate DATETIME
INSERT #HabitEntry (UserID,HabbitID,EntryDate) VALUES
(1, 1, '20150101 06:35:30'),
(1, 1, '20150102 08:35:30'),
(1, 1, '20150103 08:35:30'),
(1, 1, '20150110 09:35:30'),
(1, 1, '20150112 10:35:30'),
(1, 1, '20150115 22:35:30'),
(1, 1, '20150116 23:35:30'),
(1, 1, '20150117 00:35:30'),
(1, 1, '20150118 01:35:30'),
(1, 1, '20150122 04:35:30'),
(1, 1, '20150124 05:35:30'),
(1, 1, '20150126 15:35:30'),
(1, 1, '20150127 10:35:30'),
(2, 3, '20150101 06:35:30'),
(2, 3, '20150102 06:35:30'),
(2, 3, '20150103 02:35:30'),
(2, 3, '20150104 06:35:30'),
(2, 3, '20150105 06:35:30'),
(2, 3, '20150108 06:35:30'),
(2, 3, '20150110 06:35:30'),
(2, 3, '20150111 06:35:30'),
(2, 3, '20150112 06:35:30'),
(2, 3, '20150113 06:35:30'),
(2, 3, '20150114 06:35:30'),
(2, 3, '20150122 06:35:30'),
(2, 3, '20150123 06:35:30')
--=============================================
DECLARE @MinDate DATE, @RangeSize INT
SELECT @MinDate = DATEADD(dd, -1, MIN(he.EntryDate)) FROM #HabitEntry he
SELECT @RangeSize = DATEDIFF(dd, @MinDate, MAX(he.EntryDate) + 1) FROM #HabitEntry he
IF OBJECT_ID('tempdb..#CalRanges') IS NOT NULL DROP TABLE #CalRanges
SELECT TOP (@RangeSize)
DATEADD(dd, ROW_NUMBER() OVER (ORDER BY (SELECT NULL)), @MinDate) AS [Date],
DATEADD(hh, 3, DATEADD(dd, ROW_NUMBER() OVER (ORDER BY (SELECT NULL)), CAST(@MinDate AS DATETIME))) AS BegRange,
DATEADD(hh, 27, DATEADD(dd, ROW_NUMBER() OVER (ORDER BY (SELECT NULL)), CAST(@MinDate AS DATETIME))) AS EndRange
INTO #CalRanges
FROM sys.all_objects ao
--=============================================
;WITH cte AS (
SELECT
cr.Date,
he.UserID,
he.HabbitID,
he.EntryDate,
COALESCE(LAG(CASE WHEN he.EntryDate IS NOT NULL THEN cr.Date END, 1) OVER (PARTITION BY he.UserID, he.HabbitID ORDER BY cr.Date), '19000101') AS PrevDate
FROM
#CalRanges cr
JOIN #HabitEntry he
ON he.EntryDate BETWEEN cr.BegRange AND cr.EndRange
--AND he.UserID = 1
), cte2 AS (
SELECT
c.*,
CASE WHEN DATEDIFF(dd, c.PrevDate, c.Date) <> 1 THEN ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) END ConseqGroup
FROM cte c
WHERE c.Date <> c.PrevDate
), cte3 AS (
SELECT
c2.*,
CAST(SUBSTRING(MAX(CAST(c2.Date AS BINARY(4)) + CAST(c2.ConseqGroup AS BINARY(4))) OVER (PARTITION BY c2.UserID, c2.HabbitID ORDER BY c2.Date), 5, 4) AS INT) AS ConseqGroupFill
FROM cte2 c2
), cte4 AS (
SELECT
c3.UserID,
c3.HabbitID,
h.Name AS HabbitName,
MIN(c3.EntryDate) AS BegDate,
MAX(c3.EntryDate) AS EndDate,
COUNT(*) AS DaysInSeries
FROM
cte3 c3
JOIN #Habbit h
ON c3.HabbitID = h.ID
GROUP BY
c3.UserID,
c3.HabbitID,
c3.ConseqGroupFill,
h.Name
HAVING
COUNT(*) >= MAX(h.Target)
-- SELECT * FROM cte4
SELECT
c4.*
FROM (SELECT DISTINCT he.UserID, he.HabbitID FROM #HabitEntry he) AS a
CROSS APPLY (
SELECT TOP 1
FROM cte4 c4
WHERE a.UserID = c4.UserID
AND a.HabbitID = c4.HabbitID
ORDER BY c4.BegDate DESC
) c4
HTH,
Jason
Jason Long