Starting from version odbc 1.4, unable to prepare sql queries with "?" parameters. It worked in versions 1.3.5 and older.
What has changed in odbc?
Example for FirebirdSQL:
> packageVersion("odbc")
[1] ‘1.3.5’
> prepare <- dbSendQuery(conn, "select * from sec$users where sec$user_name = ?")
> prepare
<OdbcResult>
SQL select * from sec$users where sec$user_name = ?
ROWS Fetched: 0 [complete]
Changed: 0
> packageVersion("odbc")
[1] ‘1.4.1’
> prepare <- dbSendQuery(conn, "select * from sec$users where sec$user_name = ?")
Error: nanodbc/nanodbc.cpp:1710: 07002
[ODBC Firebird Driver]COUNT field incorrect