Move code to nested query to resolve copypaste - sql

Question

I have sql query
Here is code
SELECT tt.creationdate AS CreatedDate,
DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) AS DaysOpen,
CASE WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 180 THEN '180+ Days'
WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 150 THEN '150 - 180 Days'
WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 120 THEN '120 - 150 Days'
WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 90 THEN '90 - 120 Days'
WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 60 THEN '60 - 90 Days'
WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 30 THEN '30 - 60 Days'
WHEN DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) >= 0 THEN '0 - 30 Days'
ELSE NULL END AS TaskAging,
tms.SupportType,
tms.SupportModule,
tt.*
FROM public.tasks tt
LEFT JOIN
public.tasks_meta_support tms
ON tms.taskid = tt.Id
WHERE tt.issupportticket = 1
AND tt.supportorganizationid = 65277
AND tt.completeddate IS NULL
AND tt.isdeleted = 0
I need to move DaysOpen to nested query to reuse it in CASE
How I can do this correctly?

Answer 1

Just use a subquery:
SELECT tt.DaysOpen,
(CASE WHEN tt.DaysOpen >= 180 THEN '180+ Days'
WHEN tt.DaysOpen >= 150 THEN '150 - 180 Days'
WHEN tt.DaysOpen >= 120 THEN '120 - 150 Days'
WHEN tt.DaysOpen >= 90 THEN '90 - 120 Days'
WHEN tt.DaysOpen >= 60 THEN '60 - 90 Days'
WHEN tt.DaysOpen >= 30 THEN '30 - 60 Days'
WHEN tt.DaysOpen >= 0 THEN '0 - 30 Days'
END )AS TaskAging,
tms.SupportType,
tms.SupportModule,
tt.*
FROM (SELECT tt.*, DATEDIFF(DAY, CAST(tt.creationdate AS DATE), GETDATE()) AS DaysOpen
FROM public.tasks tt
) tt LEFT JOIN
public.tasks_meta_support tms
ON tms.taskid = tt.Id
WHERE tt.issupportticket = 1
AND tt.supportorganizationid = 65277
AND tt.completeddate IS NULL
AND tt.isdeleted = 0;
Note that the ELSE is redundant, so I removed it.

Answer 2

First I would move the GETDATE() to #Now and set it just before the query. You might get a difference in behaviour if this run 23:59:59.999, but in general you want the values fromwhen you asked, not when it's running.
Also try not to use wildcards when selecting columns.
Also, do you want all rows from public.tasks and only the matching one from publi.tasks_meta_support or all rows from public.tasksmeta_support? The order you write thing is really important here (https://learn.microsoft.com/en-us/previous-versions/sql/sql-server-2005/ms177634(v%3dsql.90)#e-using-the-sql-92-left-outer-join-syntax).
That said you could use a CTE or some a subquery.
I would go with a CTE and writing out all the columns.
Not knowing which columns there are in public.tasks maybe this subquery?
Note that I moved everything related to public.tasks to tt.
DECLARE #Now datetime;
SET #Now = #Now;
SELECT ptsq.CreatedDate,
ptsq.DaysOpen,
ptsq.TaskAging,
tms.SupportType,
tms.SupportModule,
ptsq.*
FROM (SELECT creationdate AS CreatedDate,
DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) AS DaysOpen,
CASE WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 180 THEN '180+ Days'
WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 150 THEN '150 - 180 Days'
WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 120 THEN '120 - 150 Days'
WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 90 THEN '90 - 120 Days'
WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 60 THEN '60 - 90 Days'
WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 30 THEN '30 - 60 Days'
WHEN DATEDIFF(DAY, CAST(creationdate AS DATE), #Now) >= 0 THEN '0 - 30 Days'
FROM public.tasks
WHERE issupportticket = 1
AND supportorganizationid = 65277
AND isdeleted = 0) ptsq
LEFT OUTER JOIN public.tasks_meta_support tms ON ptsq.taskid = tms.Id -- Assuming you want all rows from public.tasks.
WHERE ptsq.completeddate IS NULL -- Could probably be moved to ptsq