Microsoft Access - Merging content with identical keys into a new table - ms-access

Question

In Microsoft Access, I would like to merge a specific column from tables having an identical key (=being duplicates) into a new table.
The source table would look like this
Key Content
Apple X
Banana B
Banana D
Banana E
Banana G
Lemon A
Lemon X
Orange A
I would like to create a new table where there is only one entry per key, each key having a field consisting of all corresponding “content” fields accumulated into one field. Each “content” value should be delimited with something, example:
Apple X
Banana B<x>D<x>E<x>G
Lemon A<x>X
Orange A
I would prefer to have it like above, but it could also work if they are in different fields/columns like below:
Apple X
Banana B D E G
Lemon A X
Orange A
I would really appreciate help with this. When googling on this I have found a quit a few of third party add-ons (like this one http://www.tucows.com/preview/1586663/MS-Access-Join-Two-Tables-Software) that seems to be solving this, but surely this can be done with MS Access itself….or…?

Answer 1

Another approach would be to create the table with the two columns (Key, Content) then run the function below to copy the data into the new table. You'll have to replace "ExistingTableName" and "NewTableName" with your table names.
Sub CreateNewTable()
Dim rs As Recordset
Dim rsContent As Recordset
Dim strContent As String
'Select and loop through all keys
Set rs = CurrentDb.OpenRecordset("SELECT DISTINCT Key FROM [ExistingTableName]")
Do Until rs.EOF
'Select all content records for this key and combine into a string
Set rsContent = CurrentDb.OpenRecordset("SELECT Content FROM [ExistingTableName] WHERE Key = " & Chr(34) & Nz(rs!Key) & Chr(34))
strContent = ""
Do Until rsContent.EOF
strContent = strContent & rsContent!Content & ","
rsContent.MoveNext
Loop
If Len(strContent) > 0 Then
strContent = Mid(strContent, 1, Len(strContent) - 1)
End If
CurrentDb.Execute "INSERT INTO [NewTableName] (Key, Content) VALUES (" & Chr(34) & Nz(rs!Key) & Chr(34) & ", " & Chr(34) & Nz(strContent) & Chr(34) & ")"
rs.MoveNext
Loop
Set rs = Nothing
Set rsContent = Nothing
End Sub
I don't think there is a way to do this without VBA.
Seeing as you are using a relational database you should consider using one table to store keys and another table to store content (one content per row/record), then link them up either by using a third table or by adding the 'key' as a foreign key in the content table. I would also always use an autonumber as the primary key in all MS Access tables, if not for every other reason this is a good idea, simply to avoid corruption and enable you to change a spelling mistake like 'aple' to 'apple' without breaking your relationships.

Answer 2

One version would be to use a UDF and this query:
SELECT Distinct Fruit.Key,
ConcatADO("SELECT Content FROM Fruit WHERE Key='" & [Key] & "'","<x>","<x>")
AS AllRows
INTO NewFruit
FROM Fruit
User Defined Function (UDF)
Function ConcatADO(strSQL As String, strColDelim, strRowDelim)
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))
End If
ConcatADO = strList
Exit Function
Proc_Err:
ConcatADO = "***" & UCase(Err.Description)
End Function
Working within the query design window, you can create a crosstab
TRANSFORM Min(Fruit.Content) AS MinOfContent
SELECT Fruit.Key
FROM Fruit
GROUP BY Fruit.Key
PIVOT Fruit.Content;
Which would return
Key A B D E G X
Apple X
Banana B D E G
Lemon A X
Orange A
You could then save the crosstab and create a new query based on the cross tab. This query could be a Make Table query to get the new table, but as you can see, you have several columns.
If you have a predetermined number of possible rows for each key, there are other approaches.
Finally, you must ask yourself, is de-normalizing really the way to go?