How to join a table to a changelog table? - sql-server

Question

I have two tables related to tickets, DimTickets and want to calculate the time it takes between the CreatedDateTime and when the status was first changed to Done/Released. The DimTickets table is structured like so:
IssueKey
IssueType
Priority
Project
Status
CreatedDateTime
TEAM1-100
Story
High
Team 1
Approved for Release
2020-04-02 16:09:45
TEAM1-101
Task
Medium
Team 1
Done
2020-04-03 15:38:25
TEAM1-102
Sub-task
Low
Team 1
Done
2020-04-08 09:03:43
TEAM1-103
Bug
High
Team 1
In Progress
2020-04-13 12:18:56
TEAM1-104
Task
Medium
Team 1
Done
2020-04-16 11:40:08
TEAM2-100
Task
Medium
Team 2
Done
2020-04-17 09:06:17
TEAM2-101
Story
Medium
Team 2
Released
2020-04-17 15:55:45
TEAM2-102
Task
Low
Team 2
Done
2020-04-20 10:12:41
TEAM1-105
Task
High
Team 1
In Progress
2020-04-20 15:24:56
and a DimTicketChangelog that's structured like this:
ChangeLogID
IssueKey
FromStatus
ToStatus
ChangeLogDateTime
1
TEAM1-100
1
2
2019-06-14 15:56:03
2
TEAM1-100
2
3
2019-06-15 12:58:29
3
TEAM2-102
2
4
2019-06-16 17:58:48
4
TEAM1-100
3
5
2019-06-16 20:01:43
5
TEAM1-104
1
3
2019-06-18 10:02:39
6
TEAM1-105
4
5
2019-06-21 18:03:19
7
TEAM1-104
3
5
2019-06-24 22:05:28
8
TEAM2-102
4
6
2019-07-02 08:06:50
9
TEAM2-103
1
4
2019-07-04 11:06:50
Is there a way for me to join to DimTicketChangelog the first time a ticket is changed from a status < 5 to status 5/6 so that I can create a field that is essentially ChangeLogDateTime - CreatedDateTime to get the amount of time it took between creation of the ticket, to when it had its status changed to a resolved one?

Answer 1

Something like this should work
Explanation: You'll use the CTE to find all the instances where a ticket crossed from <5 to 5+ and "rank" them by change log date. You'll then select all of records where this ranking = 1 as that is the first instance, sorted by change log date time
EDIT: I added a date diff to satisfy your second requirement for the time it took. Your sample data is a bit interesting in terms of these dates, though with your real data you should be fine.
;WITH FindFirstChange AS (
select
t.IssueKey /*Add whatever other columns you need here*/
,t.createdDateTime
,tcl.ChangeLogDateTime
,DATEDIFF(day, t.createdDateTime ,tcl.ChangeLogDateTime) Diff
,ranking = ROW_NUMBER() OVER(PARTITION BY tcl.issuekey ORDER BY tcl.ChangeLogDateTime ASC)
FROM DimTickets t
INNER JOIN DimTicketchangelog tcl ON t.issuekey = tcl.issuekey
WHERE tcl.fromStatus <5
AND toStatus >= 5
)
SELECT *
FROM FindFirstChange
WHERE ranking = 1;

Answer 2

You have not provided any expected results and your test data doesn't really cover the criteria you describe, also your log table dates are earlier than the createDate of each ticket which makes no sense?! However see if the following works for you:
with l as (
select issuekey,changelogdatetime, Row_Number() over(partition by issueKey order by ChangeLogID) rn
from DimTicketChangeLog
where tostatus in (5,6) and FromStatus<5
)
select t.*, DateDiff(day,t.createddatetime,l.ChangeLogDateTime) Duration
from DimTickets t
left join l on l.IssueKey=t.IssueKey
where l.rn=1