I’m having an issue trying to Concat a comma separator list within SQL when the data matches. I have a table with 6 columns. I want to check if the LicenceNumbers match and then conconcatenate the ItemsNumbers into a comma separator list if the LicenceNumbers are the same.

Here is the query I’ve, but its combines the return result as 2 but adds all licences to each row

SELECT DISTINCT
    w2.Order,
    w2.Customer, 
    w2.Contract, 
    w2.Licence, 
    w2.CSSNTName, 
    CASE 
        WHEN w2.Licence= w1.LicenceTHEN
        (SELECT '[' + STRING_AGG(ISNULL(Item, ' '), ',') FROM #WorkingTable2) + ']'
        ELSE '[' + w2.Item+ ']' 
    END AS Item
FROM 
    #WorkingTable2 w2 
    INNER JOIN #WorkingTable2 w1 ON w1.Licence= w2.Licence

Table

| Order || Customer || Contract || Licence || Item || CSSNT |
| ----- || -------- || -------- || ------- || ---- || ----- |
| 5762  || 5273     || 70703US  || 420D3   || 8.10 || ABC02 |
| 5762  || 5273     || 70703US  || 420D3   || 8.9  || ABC02 |                           
| 1234  || 1111     || 123US    || 1234    || 9.10 || ABC01 |

What Results I’m looking for

| Order || Customer || Contract || Licence || Item      || CSSNT |
| ----- || -------- || -------- || ------- || --------- || ----- |
| 5762  || 5273     || 70703US  || 420D3   || [8.9,8.10]|| ABC02 |                         
| 1234  || 1111     || 123US    || 1234    || [9.10]    || ABC01 |

>Solution :

You can use a simple aggregate/group by approach

Example

Declare @YourTable Table ([Order] varchar(50),[Customer] varchar(50),[Contract] varchar(50),[Licence] varchar(50),[Item] varchar(50),[CSSNT] varchar(50))
Insert Into @YourTable Values 
 (5762,5273,'70703US','420D3',8.10,'ABC02')
,(5762,5273,'70703US','420D3',8.9,'ABC02')
,(1234,1111,'123US','1234',9.10,'ABC01')
 
Select [Order]
      ,[Customer]
      ,[Contract]
      ,[Licence]
      ,[Item]   = concat('[',string_agg(item,','),']')
      ,[CSSNT]
 From @YourTable
 Group By [Order]
      ,[Customer]
      ,[Contract]
      ,[Licence]
      ,[CSSNT]

Results