odbc select where parameters

Im enabling an apllication to use ODBC to connect to sqlserver which currently uses Oracle OCI, i have no prior knowledge about odbc use.
Im unsure how to approach where clause parameters (bind parameters)
ie Oracle OCI
select name into :name from emp where name = :a_name

via ODBC, connecting to sql server i'm attempting

select name from emp where name = ?

with,
sqlprepare
sqlbindparameter
sqlexecute
sqlbindcol
sqlfetch

all seems ok with sqlbindparameter, but sqlexecute fails with sqlstate 22001, String data, right truncation.
The question: can i use ? parameter in where conditions, if not whats the best approach.
Many Thanks.resolved. problem was oci doesnt require null terminated char string, odbc does