Concatenating field data into string via Access SQL - sql

Question

Imagine the following table
ID | Name
----------
1 | Shaun
1 | Terrence
2 | Jessica
I need to concatenate the string data in Name based on ID
ID | Name
-----------
1 | Shaun, Terrence
2 | Jessica
I am using an access database. I was thinking I could do a pivot transform and try to concatenate those fields but the problem is its hard to dynamically loop through the total field count. Any ideas?
**Edit: Order does not matter, I just want to concatenate based on ID with , and space being the delimiter. I am calling this sql code using an ADO connection from excel vba.

Answer 1

This is a similar problem I had recently trying to pivot a two column table; MS Access convert and summarise two rows into columns with unique names
'Name' is a reserved word and 'ID' is usually a auto-index with unique numbers so I changed your columns to UserID and UserName respectively.
There are some problems with creating the answer in a single subquery so I ended up doing this:
Create a temporary table with an index:
SELECT t1.UserID, t1.UserName,
(SELECT COUNT(*) + 1
FROM Table1 t2
WHERE t1.UserID = t2.UserID and t2.UserName < t1.UserName) AS [Index]
INTO Table1_indexed
FROM Table1 AS t1;
create a temporary cross tab table:
TRANSFORM First(Table1_indexed.UserName) AS FirstOfUserName
SELECT Table1_indexed.UserID FROM Table1_indexed
GROUP BY Table1_indexed.UserID
PIVOT Table1_indexed.Index;
concatenate the name fields
SELECT Table1_crosstab.UserID, Table1_crosstab.[1], Table1_crosstab.[2],
IIf([1] Is Not Null,[1]) & IIf([2] Is Not Null,", " & [2]) AS ConcatenatedName
FROM Table1_crosstab;
If you have more than two name fields you could adjust the concatenate query to the maximum number you expect.
It might be possible to merge these steps into a single query but I've not yet found a way.

Answer 2

You can create a Visual Basic Function and call it from your query, e.g. something like this (assuming your table is called Names):
Public Function ListOfNames(id as Integer) As String
Dim rs As Recordset
Set rs = CurrentDb.OpenRecordset("Select Name from Names where ID=" & id, DbOpenSnapshot)
ListOfNames = ""
If Not (rs.EOF and rs.BOF) Then
rs.MoveFirst
Do Until rs.EOF = True
If (Len(ListOfNames) > 0) Then
ListOfNames = ListOfNames & “, “
End If
ListOfNames = ListOfNames & rs!Name
rs.MoveNext
Loop
End If
rs.Close
End Function
Then you can for instance call the function from your query:
SELECT ID, ListOfNames([ID]) as Name From Names Group By ID