SSRS -- Multi-value parameter string manipulation

Question

Context: I have an SSRS report with a multi-value parameter. The report passes the multi-value parameter to a stored procedure that assigns it to a variable of an nvarchar type. This variable contains unique IDs that map to values in the DB that are actually stored as an int data type.

Details: Basically I need to a) Modify the ssrs report to allow for multi-value entry (which i've already done) b) split_string the nvarchar variable into consumable int type pieces c) process the query with these pieces d) re-construct the string to present the query results in a concatenated fashion per user requirements

Questions: Can you please assist in finding the most efficient way to perform these transformations in the proc I've (attempted) to draft below?

Side note: While I've found some posts related to handling multi-value ssrs parameters in procs here , here and here -- they aren't fixes that apply to my specific scenario given the multiple rounds of transformation needed.

/*This is the parameter supplied by the SSRS report that needs to be split, just declared here for commentary purposes
DECLARE @p_catalog_id nvarchar(max);
SET @p_catalog_id = '163650,163651,163652,163653,163654,163655,163656,163657,310415';
*/

BEGIN 

WITH EPV_IDs
AS
    (
        SELECT h.CATALOG_ID,
               h.PARENT_Catalog_ID as 'Series Collection ID',
               c.catalog_template as Template,
               d.CATALOG_ID as 'EPV ID'
        FROM [RDW_DIV38].[dbo].[Catalog_LINK_Catalog] as h 
          inner join [RDW_DIV38].[dbo].[Catalog] as c on c.Catalog_ID = h.CATALOG_ID
          left join [RDW_DIV38].[dbo].[Catalog_LINK_Catalog] as d on d.PARENT_Catalog_ID = h.PARENT_Catalog_ID
          inner join [RDW_DIV38].[dbo].[Catalog] as f on f.catalog_id=H.PARENT_Catalog_ID
        WHERE c.catalog_template = 'Episode Version'
          and f.catalog_template='series Collection'
          and c.Catalog_STATUS not in ('Withdrawn', 'Cancelled')
          and f.Catalog_STATUS not in ('Withdrawn', 'Cancelled')
          and d.Catalog_ID = @p_catalog_id
    ), 
X
AS
    (
        SELECT  EPV_IDs.[Series Collection ID],
                EPV_IDs.[Template],
                EPV_IDs.[EPV ID],
                COUNT(EPV_IDs.[EPV ID])as 'All EPVs'
        FROM EPV_IDs
        GROUP BY EPV_IDs.[Series Collection ID], EPV_IDs.[Template], EPV_IDs.[EPV ID]
    ),
y
AS
    (
        SELECT X.[Series Collection ID], 
               X.[Template],
               case when COUNT(X.[EPV ID]) = X.[All EPVs] Then 'Yes' Else 'No' ENd as 'Full?',
               COUNT(X.[EPV ID]) as 'EPVs Found',
               X.[All EPVs],STRING_AGG(X.[EPV ID],',')as 'EPV IDs'
        FROM X
        GROUP BY X.[Series Collection ID] ,X.[Template],x.[All EPVs]
    ), 
A
AS
    (
        SELECT x.[EPV ID],
               y.[Series Collection ID],
               y.[Template],
               STRING_AGG(y.[Full?],'/')as [Full?],
               y.[EPVs Found],
               y.[All EPVs],
               y.[EPV IDs]
        FROM y
        inner join x on x.[Series Collection ID]=y.[Series Collection ID]
        GROUP BY x.[EPV ID], y.[Series Collection ID], y.[Template], y.[EPVs Found], y.[All EPVs], y.[EPV IDs]
    )
        SELECT DISTINCT a3.[Series Collection ID] as Series_Collection_ID,
                        a3.[Template],
                        a.[Full?] as [Full],
                        a3.[EPVs Found] as EPVs_Found,
                        a3.[All EPVs] as All_EPVs,
                        a3.[EPV IDs] as EPV_IDs
        FROM a
        left join a as a3 on  a3.[EPV ID]=a.[EPV ID]
        WHERE not exists (

                           SELECT 1
                           FROM a a2
                           WHERE a2.[EPV ID] =a.[EPV ID] and  a2.[Full?] = 'Yes'

                         )
        UNION
        SELECT a.[Series Collection ID] as Series_Collection_ID,
               a.[Template],
               a.[Full?] as [Full],
               a.[EPVs Found] as EPVs_Found,
               a.[All EPVs] as All_EPVs,
               a.[EPV IDs] as EPV_IDs
        FROM a
        WHERE a.[Full?]='Yes'

END

Answer 1

if your database is 2016 then you can just use string_split: Replace

and d.Catalog_ID = @p_catalog_id

with

and CAST(d.Catalog_ID as varchar(10)) IN (SELECT value FROM STRING_SPLIT(@p_catalog_id, ',')

Otherwise i'd suggest you use the FOR XML PATH approach - lots of egs out there & others too: https://sqlperformance.com/2012/07/t-sql-queries/split-strings