One to Many Relationship, Concatenate data

Posted on 2005-04-25
Medium Priority
Last Modified: 2008-02-01

I am having some trouble concatenating data from the table on the many side of a one to many relationship.

I have two tables:

[EmpID] text, primary key (this is field filled with numbers, but is not used for any mathematical computation)
[FirstName] text
[LastName] text
{other fields that aren't used for this issue}

[DepID] AutoNumber, primary key
[EmpID] text

the two tables are used to show each employee's dependents.  Let me give an example:

0001 | John | Doe
0002 | Joe | Stump

1 | 0001 | Spouse | Jane
2 | 0001 | Child | Jim
3 | 0001 | Child | Shana
4 | 0002 | Spouse | Bess
5 | 0002 | Child | Bob

What I'd like to end up with is a query that will concatenate the [DepName] field on the many side of the table into a string.  Like so:

0001 | John | Doe | Jane, Jim, Shana
0002 | Joe | Stump | Bess, Bob.

I tried using the following code in a module, but when I called the function in this Query:
SELECT TblEmpInfo.*, fConcatFld("TblEmpDepend","EmpID","DepName","String",[EmpID]) AS DepNames
FROM TblEmpInfo;
I kept getting the "type mismatch" # 13 error

this is the code for the function (which I got from http://www.mvps.org/access/modules/mdl0004.htm )

'************ Code Start **********
'This code was originally written by Dev Ashish
'It is not to be altered or distributed,
'except as part of an application.
'You are free to use it in any application,
'provided the copyright notice is left unchanged.
'Code Courtesy of
'Dev Ashish
Function fConcatChild(strChildTable As String, _
                    strIDName As String, _
                    strFldConcat As String, _
                    strIDType As String, _
                    varIDvalue As Variant) _
                    As String
'Returns a field from the Many table of a 1:M relationship
'in a semi-colon separated format.
'Usage Examples:
'   ?fConcatChild("Order Details", "OrderID", "Quantity", _
                "Long", 10255)
'Where  Order Details = Many side table
'       OrderID       = Primary Key of One side table
'       Quantity      = Field name to concatenate
'       Long          = DataType of Primary Key of One Side Table
'       10255         = Value on which return concatenated Quantity
Dim db As Database
Dim rs As Recordset
Dim varConcat As Variant
Dim strCriteria As String, strSQL As String
    On Error GoTo Err_fConcatChild
    varConcat = Null
    Set db = CurrentDb
    strSQL = "Select [" & strFldConcat & "] From [" & strChildTable & "]"
    strSQL = strSQL & " Where "
    Select Case strIDType
        Case "String":
            strSQL = strSQL & "[" & strIDName & "] = '" & varIDvalue & "'"
        Case "Long", "Integer", "Double":    'AutoNumber is Type Long
            strSQL = strSQL & "[" & strIDName & "] = " & varIDvalue
        Case Else
            GoTo Err_fConcatChild
    End Select
    Set rs = db.OpenRecordset(strSQL, dbOpenSnapshot)

    'Are we sure that 'sub' records exist
    With rs
        If .RecordCount <> 0 Then
            'start concatenating records
            Do While Not rs.EOF
                varConcat = varConcat & rs(strFldConcat) & ";"
        End If
    End With
    'That's it... you should have a concatenated string now
    'Just Trim the trailing ;
    fConcatChild = Left(varConcat, Len(varConcat) - 1)
    Set rs = Nothing: Set db = Nothing
    Exit Function
    Resume Exit_fConcatChild
End Function

'************ Code End **********

Does anyone have any ideas as to what could be giving me the type mismatch error?  If so, any ideas as to how I could fix it?

Any help is greatly appreciated, as always.

Question by:wolfeman76
  • 2
LVL 11

Expert Comment

ID: 13862606
The only problem I can see is the name of the function you are calling should be


and not


your query should be as follows:

SELECT TblEmpInfo.*, fConcatChild("TblEmpDepend","EmpID","DepName","String",[EmpID]) AS DepNames
FROM TblEmpInfo

But the error message suggests that one of your fields may not have the datatype you think it has.

LVL 11

Expert Comment

ID: 13862623
Check that the datatype of EmpID really is text


Author Comment

ID: 13866767
Um. Yeah.

I found my mistake (aside from calling the wrong function)

This database uses elements of ADO so the recordset needed to be declared a DAO recordset
so instead of:
 Dim rs As Recordset

It should have been
 Dim rs As DAO.Recordset

stupid computers doing what they're told...Geez.

Steve, Thanks for your help

Accepted Solution

modulo earned 0 total points
ID: 14456964
PAQed with points refunded (250)

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