SQL Server parameter substitution

Hi,

I'm using FreeTDS on Ubuntu (through pymssql and SQLAlchemy) to connect to
my SQL Server and I'm running into an issue where I can't seem to pass
parameterized SQL statements through to SQL Server.  I can create my nice
neat parameterized statements in SQL Alchemy that look like this:

SELECT * FROM Customers WHERE CustomerId = :CustomerId;

but by the time it gets to the DB, it looks like this:

SELECT * FROM Customers WHERE CustomerId = 572;

The actual parameter substitution appears to be occurring in the pymssql
layer, but they tell me that that's because of a limitation in FreeTDS,
where parameterized SQL is not handled.  Is that true?

This creates a problem for us because every statement is fairly unique
(since the ids are embedded in the SQL) and thus we rarely get to re-use
execution plans.

Please let me know if my understanding about parameterized SQL not being
supported by FreeTDS is correct.

Many thanks!

-Mike