When I try to run this query in Access through the ODBC interface into a MySQL database I get an "Expression too complex in query expression" error. The essential thing I'm trying to do is translate abbreviated names of languages into their full body English counterparts. I was curious if there was some way to "trick" access into thinking the expression is smaller with sub queries, or if someone else had a better idea of how to solve this problem. I thought about making a temporary table and doing a join on it, but that's not supported in Access SQL.

Just as an FYI, the query worked fine until I added the big long IFF chain. I tested the query on a smaller IFF chain for three languages, and that wasn't an issue, so the problem definitely stems from the huge IFF chain (It's 26 deep). Also, I might be able to drop some of the options (like combining the different forms of Chinese or Portuguese)

As a test, I was able to get the SQL query to work after paring it down to 14 IFF() statements, but that's a far cry from the 26 languages I'd like to represent.

SELECT TOP 5 Count( * ) AS [Number of visits by language], IIf(login.lang="ar","Arabic",IIf(login.lang="bg","Bulgarian",IIf(login.lang="zh_CN","Chinese (Simplified Han)",IIf(login.lang="zh_TW","Chinese (Traditional Han)",IIf(login.lang="cs","Czech",IIf(login.lang="da","Danish",IIf(login.lang="de","German",IIf(login.lang="en_US","United States English",IIf(login.lang="en_GB","British English",IIf(login.lang="es","Spanish",IIf(login.lang="fr","French",IIf(login.lang="el","Greek",IIf(login.lang="it","Italian",IIf(login.lang="ko","Korean",IIf(login.lang="hu","Hungarian",IIf(login.lang="nl","Dutch",IIf(login.lang="pl","Polish",IIf(login.lang="pt_PT","European Portuguese",IIf(login.lang="pt_BR","Brazilian Portuguese",IIf(login.lang="ru","Russian",IIf(login.lang="sk","Slovak",IIf(login.lang="sl","Slovenian","IIf(login.lang="fi","Finnish",IIf(login.lang="sv","Swedish",IIf(login.lang="tr","Turkish","Unknown")))))))))))))))))))))))))) AS [Language]
FROM login, reservations, reservation_users, schedules
WHERE (reservations.start_date Between DATEDIFF('s','1970-01-01 00:00:00',[Starting Date in the Following Format YYYY/MM/DD]) And DATEDIFF('s','1970-01-01 00:00:00',[Ending Date in the Following Format YYYY/MM/DD])) And reservations.is_blackout=0 And reservation_users.memberid=login.memberid And reservation_users.resid=reservations.resid And reservation_users.invited=0 And reservations.scheduleid=schedules.scheduleid And scheduletitle=[Schedule Title]
GROUP BY login.lang
ORDER BY Count( * ) DESC;

@ Michael Todd

I completely agree. The list of languages should have been a table in the database and the login.lang should have been a FK into that table. Unfortunately this isn't how the database was written, and it's not really mine to modify. The languages are placed into the login.lang field by the PHP running on top of the database.