Question

I’m looking for an Access 2007 equivalent to SQL Server’s COALESCE function.

In SQL Server you could do something like:

Person

John Steve Richard 

SQL

DECLARE @PersonList nvarchar(1024) SELECT @PersonList = COALESCE(@PersonList + ',','') + Person FROM PersonTable  PRINT @PersonList 

Which produces: John, Steve, Richard

I want to do the same but in Access 2007.

Does anyone know how to combine rows like this in Access 2007?

Answer 1

Here is a sample User Defined Function (UDF) and possible usage.

Function:

Function Coalsce(strSQL As String, strDelim, ParamArray NameList() As Variant) Dim db As Database Dim rs As DAO.Recordset Dim strList As String      Set db = CurrentDb      If strSQL <> '' Then         Set rs = db.OpenRecordset(strSQL)          Do While Not rs.EOF             strList = strList & strDelim & rs.Fields(0)             rs.MoveNext         Loop          strList = Mid(strList, Len(strDelim))     Else          strList = Join(NameList, strDelim)     End If      Coalsce = strList  End Function 

Usage:

SELECT documents.MembersOnly,      Coalsce('SELECT FName From Persons WHERE Member=True',':') AS Who,      Coalsce('',':','Mary','Joe','Pat?') AS Others FROM documents; 

An ADO version, inspired by a comment by onedaywhen

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 

From: http://wiki.lessthandot.com/index.php/Concatenate_a_List_into_a_Single_Field_%28Column%29