Calling Suer Defined Functions From Within Access Query... And More!

Hi all,

I have quite a large select query that pulls in Date values from different tables. The end result is a list of records, where each record has 7 types of dates, put in columns A, B, C, D, E, F, G. What I need to do is, for each record to compare dates in those columns and put the LATEST one of them in the column MDATE.

I've tried using IIF function, but it grows exponentially with the number of values involved, and it can only handle 5 values before its cause error "too large". Alternatively I thought I could write a function to return the max date and call it from within the query, something along the lines of "select *, fnMaxDate(A, B, C, D, E, F, G) as MDATE from tblBLAH etc". The function is:

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Public Function fnMaxDate(a As Date, b As Date, c As Date, d As Date, e As Date, f As Date, g As Date) As Date

Dim Temp As Date
Temp = Nz(a, "01/01/1901")

If Nz(b, "01/01/1901") > Temp Then Temp = b
If Nz(c, "01/01/1901") > Temp Then Temp = c
If Nz(d, "01/01/1901") > Temp Then Temp = d
If Nz(e, "01/01/1901") > Temp Then Temp = e
If Nz(f, "01/01/1901") > Temp Then Temp = f
If Nz(g, "01/01/1901") > Temp Then Temp = g

fnMaxDate = Temp

End Function
----------------------

I've put a break at the start of the function, to see what it'll come up with but when running the query it didn't appear to call it. All values in MDATE where #error.

Can someone advise me, please, on the best way of picking the LATEST date? I'd also appreciate it if you tell me why the function didn't get called, as I was quite certain it is possible to call user defined functions from within the query.

Cheers,

Kat