MS Access - SQL Query for Max Date - sql

Question

I am creating a schedule calendar which has been working great, but I want to adjust the SQL so that it only shows when the next job has to be done. I was thinking the best way to achieve this would be via the MAX() function, however when i run the code Access doesn't seem to like it.
Public Sub LoadArray()
'This sub loads an array with the relevant variables from a query
Dim db As Database
Dim rs As Recordset
Dim rsFiltered As Recordset
Dim strQuery As String
Dim i As Integer
Dim Text23 As Integer
On Error GoTo ErrorHandler
Text23 = Forms.frmPreventativeMenu.Form.CompanyName.Value
strQuery = "SELECT tblWMYReports.Company, tblWMYReports.Machine, MAX(tblWMYReports.NextDate), tblWMYReports.WMY " _
& "FROM tblWMYReports " _
& "WHERE (((tblWMYReports.Company)= " & Text23 & " ));"
Set db = CurrentDb
Set rs = db.OpenRecordset(strQuery)
With rs
If Not rs.BOF And Not rs.EOF Then
'Ensures the recordset contains records
For i = 0 To UBound(MyArray)
'Will loop through the array and use dates to filter down the query
'It firsts checks that the second column has true for its visible property
If MyArray(i, 1) = True Then
.Filter = "[NextDate]=" & MyArray(i, 0)
'To filter you must open a secondary recordset and
'Use that as the basis for a query
'This makes sense as you are building a query on a query
Set rsFiltered = .OpenRecordset
If Not rsFiltered.BOF And Not rsFiltered.EOF Then
'If the recordset is not empty then you are able
'to extract the text from the values provided
Do While Not rsFiltered.EOF = True
MyArray(i, 2) = MyArray(i, 2) & vbNewLine & DLookup("MachineName", "tblMachine", "MachineID=" & rsFiltered!Machine)
MyArray(i, 2) = MyArray(i, 2) & " - " & DLookup("WMY", "tblWMY", "ID=" & rsFiltered!WMY)
rsFiltered.MoveNext
Loop
End If
End If
Next i
End If
.Close
End With
ExitSub:
Set db = Nothing
Set rs = Nothing
Exit Sub
ErrorHandler:
MsgBox "There has been an error. Please reload the form.", , "Error"
Resume ExitSub
End Sub

Answer 1

You are going to aggregate one column with an aggregate function like Sum(), Max(), Count() or similar, then every other column that isn't being aggregated must show up in the SQL's GROUP BY clause:
strQuery = "SELECT tblWMYReports.Company, tblWMYReports.Machine, MAX(tblWMYReports.NextDate), tblWMYReports.WMY " _
& "FROM tblWMYReports " _
& "WHERE (((tblWMYReports.Company)= " & Text23 & " )) " _
& "GROUP BY tblWMYReports.Company, tblWMYReports.Machine, tblWMYReports.WMY;"
I can't guarantee that is going to do what you want it to, since I'm not familiar with your data, code, or application, but it should get you through the error.

Answer 2

You must use a properly formatted string expression for the date value:
.Filter = "[NextDate] = #" & Format(MyArray(i, 0), "yyyy\/mm\/dd") & "#"