Concatenate multiple rows in one field in Access? [duplicate] - sql

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Ms Access Query: Concatenating Rows through a query
I have a table that has many columns, but two of interest: Order Number and Product Type. Currently the table has multiple Product Types per Order. If the customer ordered phone service, TV service and Internet service, then there would be three records - one for each service but all having the same order number. I want to create a reference table to store a concatenated string with all of the services the customer ordered. This way I can summarize my data using this more logical method. I'm using a standard Access 2010 database.
**Current table:**
Order Number | Product Types
100001 | TV
100001 | Phone
100001 | Internet
100002 | Phone
100003 | TV
100003 | Internet
Desired reference table
100001 | TV/Phone/Internet
100002 | Phone
100003 | TV/Internet

Answer 1

Allen Browne provides a function which you may find useful for this: Concatenate values from related records. Save that function's code in a standard module.
SELECT DISTINCT
[Order Number],
ConcatRelated("[Product Types]",
"YourTable",
"[Order Number] = " & [Order Number],
"[Product Types]",
"/"
) AS All_Product_Types
FROM YourTable;
I tested that query in Access 2007 with your sample data saved in a table named "YourTable". It returned the results you asked for. However, this only works from within an Access session. If you wanted to run this query from outside Access (like from ASP), user-defined functions are not available, so you would get an error about ConcatRelated() not recognized.
So you can use a query to retrieve the concatenated values whenever you need them. However if you store those concatenated values, they can quickly be out of sync with changes to the base table's data.

Answer 2

If I understand the question, you're asking how to get the order numbers of just those orders who have TV, AND phone, AND internet. If you're just interested in those order numbers you could run a query like:
SELECT Distinct Table1.OrderNumber
FROM (Select OrderNumber from Table1 where [product types]= "Internet") AS i
INNER JOIN ((Select OrderNumber from Table1 where [product types]="Phone") AS p
INNER JOIN ((Select OrderNumber from Table1 Where [product types]= "TV") AS tv
INNER JOIN Table1 ON tv.OrderNumber = Table1.OrderNumber) ON p.OrderNumber = Table1.OrderNumber) ON i.OrderNumber = Table1.OrderNumber;

Answer 3

As was pointed out by onedaywhen in an early post on SO, this is easier with ADO:
Sample query:
SELECT [Order Number],
ConcatADO("SELECT [Product Types] FROM Orders
WHERE [Order Number]=" & [Order Number],", "," : ") AS Cat
FROM Orders
GROUP BY [Order Number], 2;
Function using ADO
Function ConcatADO(strSQL As String, strColDelim, _
strRowDelim, ParamArray NameList() As Variant)
Dim rs As New ADODB.Recordset
Dim strList As String
On Error GoTo Proc_Err
If strSQL <> "" Then
rs.Open strSQL, CurrentProject.Connection
strList = rs.GetString(, , strColDelim, strRowDelim)
strList = Mid(strList, 1, Len(strList) - Len(strRowDelim))
Else
strList = Join(NameList, strColDelim)
End If
ConcatADO = strList
Exit Function
Proc_Err:
ConcatADO = "***" & UCase(Err.Description)
End Function

Answer 4

You should not create a reference table that concatenates records. That is denormalizing the database.
You can try a crosstab query like below, but I have not tested it. You can read here for more information.
TRANSFORM First([Product Types]) AS Product
SELECT [Order Number], First([Product Types])
FROM CurrentTable
GROUP [Order Number]