Coding to extract data based on a date (in SQL) using a FileMaker Pro ODBC connection

This is giving me a royal brain hernia.

Here's the stripped-down SQL query:

"SELECT ATTENDANCE.ATT_DATE
FROM ATTENDANCE
WHERE ATTENDANCE.ATT_DATE='MAIN::ReportFromDate__gct'
AND ATTENDANCE.YEARID=22
AND ATTENDANCE.PERIODID>0"

I get the "ODBC Error: [Actual][Oracle] ORA-01858: a non-numeric character was found where a numeric was expe" error message as is; I've tried numerous different ways of coding the WHERE ATTENDANCE.ATT_DATE='MAIN::ReportFromDate__gct' line but every one results in failure. I'm at the point where I'm going to slaughter a chicken, wave it over my head three times, and mumble an incantation in Cantonese.

So, what's the correct syntax to grab the data from the ReportFromDate__gct field?

TIA for your help!