Select back a comma delimited list grouped by an ID

Question

I\'ve got the following tables:

EntryTag
---------
EntryID
TagID

Example putput (EntryID, TagID):

1 2
1 4
1 5
2 3
2 4
2 5
e         


        

Answer 1

DECLARE @TableOne TABLE
(
    EntryID INT,
    TagID INT
)

DECLARE @TableTwo TABLE
(
    TagID INT,
    Name NVARCHAR(100)
)

INSERT INTO @TableOne (EntryID,TagID)
VALUES  (1,2)
       ,(1,4)
       ,(1,5)
       ,(2,3)
       ,(2,4)
       ,(2,1)

INSERT INTO @TableTwo (TagID,Name)
VALUES  (1,'Daniel')
       ,(2,'Samuel')
       ,(3,'Petkov')
       ,(4,'Ivan')
       ,(5,'Jack')

/* 
    In this CTE we are going to format the values int the folowing way:

    1   2,4,5
    2   1,3,4

    Or for eaech EntryIDs, we will have all its TagIDs 

*/
;WITH CTE AS
(
    SELECT DISTINCT EntryID
          ,(SELECT SUBSTRING((SELECT ',' + CAST(TagID AS NVARCHAR(10)) FROM @TableOne AS T1 WHERE T1.EntryID=T2.EntryID ORDER BY TagID FOR XML PATH('')),2,200)) AS CSVTags
    FROM @TableOne T2

)
/*
    Here we are replacing the EntryIDs with their names from the @TableTwo:
*/
SELECT EntryID
      ,(SELECT SUBSTRING((SELECT ',' + Name FROM @TableTwo WHERE CSVTags LIKE '%'+CAST(TagID AS NVARCHAR(5))+'%' ORDER BY TagID FOR XML PATH('')),2,200) AS CSV) 
FROM CTE