When calling SQLDescribeParam in the Microsoft SQL Server ODBC driver, you get an error return with the diagnostic text:
"Incorrect Syntax near the Keyword 'by'"
This was a bug in MDAC 2.6 and is fixed in MDAC 2.6 sp1.
It happens if you have a column named "c", "ca" or "cas" and you call SQLDescribeParam, because the driver is checking for a CASE statement and does the check incorrectly.