MS Access 2013 - Getting unfounded Division by zero error

Question

I have a routine that writes totals to textboxes to prevent expensive 'Dlookup' processing time.

Some of the totals produce a percentage rate so depend on a denominator.

The error seems to be due to lag of some sort because the denominators are never blank or zero. For example, as long as there are values in this database - which there are always an abundance of, these denominators will never be zero.

At any rate, here is the line that gets the error ( I get an error 11)

Dim db As DAO.Database
Dim rs As DAO.Recordset
Dim rsSP As DAO.Recordset

Set db = CurrentDb
--->Set rs = db.OpenRecordset("TOTALS_FINAL", dbOpenSnapshot)

What can I do to trap this error? It only happens occasionally and when I tell the use to restart the database (which frees up some resources) it usually corrects the problem.

Here is the SQL for TOTALS final

SELECT
    "Total Program" AS BL
   ,TOTALS_COB_ALL_TOTALS.AFP_ AS AFP
   ,TOTALS_COB_ALL_TOTALS.ALLT_ AS ALLT
   ,TOTALS_COB_ALL_TOTALS.SP_C_ AS SP_C
   ,TOTALS_COB_ALL_TOTALS.SP_O_ AS SP_O
   ,TOTALS_COB_ALL_TOTALS.COMMITS_ AS COMMITS
   ,TOTALS_COB_ALL_TOTALS.OBS_ AS OBS
   ,TOTALS_COB_ALL_TOTALS.RA_ AS RA
   ,IIF([SP_C_] = 0, 0, [COMMITS_] / [SP_C_]) AS COM_SP_RATE
   ,IIF([SP_O_] = 0, 0, [OBS_] / [SP_O_]) AS OBS_SP_RATE
   ,IIF(Nz([AFP_], 0) = 0, 0, Nz([OBS_], 0) / [AFP_]) AS OB_AFP_RATE
   ,TOTALS_COB_ALL_TOTALS.UNC_ AS UNC
   ,TOTALS_COB_ALL_TOTALS.AVL_ AS AVL
   ,TOTALS_COB_ALL_TOTALS.ACW_ AS ACW
   ,7999 AS SO
FROM
    TOTALS_COB_ALL_TOTALS;

The query right before it just collects totals that are used to produce the final percentages

Answer 1

The reason is, that IIf always evaluates both expressions even though only one is used.

So use a "double-iif" that divides by one and not zero:

,IIF([SP_C_] = 0, 0, [COMMITS_] / IIf([SP_C_] = 0, 1, [SP_C_])) AS COM_SP_RATE
,IIF([SP_O_] = 0, 0, [OBS_] / IIf([SP_O_] = 0, 1, [SP_O_])) AS OBS_SP_RATE
,IIF(Nz([AFP_], 0) = 0, 0, [OBS_] / IIf(Nz([AFP_], 0) = 0, 1, [AFP_]) AS OB_AFP_RATE