How to write a multi-parameter CTE script? - tsql

Question

I am trying to write a TSQL script for an SSRS report that uses a CTE to select records based on the parameters chosen. I'm looking for the most efficient way to do this, either all in TSQL and/or SSRS. I have 4 parameters which can be set to NULL (All values) or one specific value. Then in my CTE, I have the following line:
ROW_NUMBER() over(partition by G.[program_providing_service],G.people_id
order by G.[actual_date] desc) as rowID
This above CTE is for the case when Program is NULL and People is not null. My 4 parameters are:
Program, Facility, Staff, and People.
So I only want to partition values when they are NULL. Currently I implement this by one CTE depending on the parameter values. For example, if they choose NULL for all parameters except People, then this CTE would look like:
ROW_NUMBER() over(partition by G.people_id
order by G.[actual_date] desc) as rowID
Or if all 5 parameters are null:
ROW_NUMBER() over(partition by G.[program_providing_service], G.[site_providing_service], G.staff_id, G.people_id
order by G.[actual_date] desc) as rowID
If they do not choose NULL for any of the 4 parameters, then I probably do not need to partition by any field since I just want the top 1 record ordered by actual_date descending. This is what my CTE looks like:
;with cte as
(
Select distinct
G.[actual_date],
G.[site_providing_service],
p.[program_name],
G.[staff_id],
G.program_providing_service,
ROW_NUMBER() over(partition by G.[program_providing_service],G.people_id
order by G.[actual_date] desc) as rowID
From
event_log_rv G With (NoLock)
WHERE
...
AND (#ClientID Is Null OR [people_id]=#ClientID)
AND (#StaffID Is Null OR [staff_id] = #StaffID)
AND (#FacilityID Is Null OR [site_providing_service] = #FacilityID)
AND (#ProgramID Is Null OR [program_providing_service] = #ProgramID)
and (#SupervisorID is NULL OR staff_id in (select staff_id from #supervisors))
)
SELECT
[actual_date],
[site_providing_service],
[program_name],
[staff_id],
program_providing_service,
people_id,
rowID
FROM cte WHERE rowid = 1
ORDER BY [Client_FullName]
where the ROW_NUMBER line varies depending on the parameters chosen. Currently I have 5 IF statements in this TSQL script that look like:
IF #ProgramID IS NOT NULL AND #ClientID IS NULL
BEGIN
...
END
with one CTE in each of these IF statements:
IF #FacilityID IS NOT NULL AND #ClientID IS NULL
BEGIN
...
END
IF #ProgramID IS NOT NULL AND #ClientID IS NULL
BEGIN
...
END
IF #StaffID IS NOT NULL AND #ClientID IS NULL
BEGIN
...
END
IF #ClientID IS NOT NULL
BEGIN
...
END
How can I code for all possible options, whether they choose NULL or else specific values?

Answer 1

OMG.... it took me long time to try to understand what you want to do. There is some contradiction in your description. Pleas revist your description. Like you said you only want to partition values when they are NULL; then you also said, when they choose NULL for all parameter except for people, then you partition on people....
No matter what way you want to achieve, partition on 'null' or 'not null', you can construct dynamic sql to achieve this, instead of adding a lot of [if...else]
Following code is pseudo, definitely not tested. Just give you a hint. The following code has one assumption, which is your parameters have priority in partition order, for example, if Program is not null (or null), Program is in the first location.
declare #sql varchar(max)
set #sql = '
;with cte as
(
Select distinct
G.[actual_date],
G.[site_providing_service],
p.[program_name],
G.[staff_id],
G.program_providing_service,
ROW_NUMBER() over(partition by
'
if(#progarm is null)
set #sql = #sql + 'G.[program_providing_service],'
if(#facility is null)
set #sql = #sql + 'G.[site_providing_service],'
if(#staff is null )
set #sql = #sql + 'G.staff_id,'
if(#people is null)
set #sql = #sql + 'G.people_id'
set #sql = #sql + '
order by G.[actual_date] desc) as rowID
From
event_log_rv G With (NoLock)
WHERE
...
AND (#ClientID Is Null OR [people_id]=#ClientID)
AND (#StaffID Is Null OR [staff_id] = #StaffID)
AND (#FacilityID Is Null OR [site_providing_service] = #FacilityID)
AND (#ProgramID Is Null OR [program_providing_service] = #ProgramID)
and (#SupervisorID is NULL OR staff_id in (select staff_id from #supervisors))
)
SELECT
[actual_date],
[site_providing_service],
[program_name],
[staff_id],
program_providing_service,
people_id,
rowID
FROM cte WHERE rowid = 1
ORDER BY [Client_FullName]
'
exec(#sql)