How Can I use this function in a Query?

Posted on 2013-10-29
Medium Priority
Last Modified: 2013-10-30
I have stored the following function in a module and I have tried to use it in a query as follows but I am getting a Data Type mismatch error when I run the query yet when I step through the function the result is a date field as expected. What am I doing wrong?

SELECT Tasks.*, Components.*, fStartOrder([StartOn],[DueDate]) AS Sort1, Nz([pkTaskType],"zzzz") AS Expr2, Nz([Priority],999) AS Expr3
FROM Tasks LEFT JOIN (Components LEFT JOIN tblTaskTypes ON Components.TaskType = tblTaskTypes.pkTaskType) ON Tasks.ID = Components.fkID
WHERE (((Components.Completed)<>True))
ORDER BY fStartOrder([StartOn],[DueDate]), Tasks.ID;

Function fStartOrder(StartOn As Date, DueDate As Date) As Date
    'Used in query to set the order of the StartOn value
    Dim StartOrder As Date
    If IsNull(StartOn) And IsNull(DueDate) Then
        StartOrder = Date
    ElseIf IsNull(DueDate) And Not IsNull(StartOn) Then
        StartOrder = StartOn
    ElseIf IsNull(StartOn) And Not IsNull(DueDate) Then
        StartOrder = DueDate
    ElseIf DueDate <= StartOn Then
        StartOrder = DueDate
    ElseIf StartOn < DueDate Then
        StartOrder = StartOn
    Else 'trap for missing entries
        StartOrder = #1/1/2001#
    End If
   fStartOrder = StartOrder
End Function
Question by:Rob4077
LVL 120

Accepted Solution

Rey Obrero (Capricorn1) earned 2000 total points
ID: 39609050
try changing this line

Function fStartOrder(StartOn As Date, DueDate As Date) As Date


Function fStartOrder(StartOn, DueDate) As Date

or leave as is
Function fStartOrder(StartOn As Date, DueDate As Date) As Date

but change the way you call the function in the query, like this

LVL 31

Expert Comment

by:Helen Feddema
ID: 39609116
Or do some testing for valid dates in the function itself, using the IsDate function.  Just checking for the value not being Null may not be enough.

Author Comment

ID: 39610921
Thanks for your suggestions. The fields DueDate and StartOn are both defined as date fields in the table so I thought that passing them to a function as date fields would work. Looks like it wasn't feeding information where the date field was null. As suggested by Capricorn1, changing it to a variant made it work (i.e. Function fStartOrder(StartOn, DueDate) As Date).

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