Inserting Empty Values Into NOT NULL Columns Via ODBC

We are writing a C application that is using ODBC to insert records
into a database. We have a NOT NULL column that can legitimately have
an empty value, i.e. we know the value and it is empty (i.e. a zero
length string).

We are using SQLBindParameter() to bind a variable to the
parameterized insert statement <<in the form: INSERT INTO table VALUES
(?, ?, ?)>>. We are using SQLExecDirect() to process the SQL.

We are running into the problem where ODBC is converts the empty (zero
length) string into a NULL value and this errors due to the fact that
the column is defined as NOT NULL.

We do not want to redefine the column as NULL, becasue my
understanding of the correct usage of a NULL column is to indicate
that a value is unknown or meaningless... in our case we know the
value (it is empty) and an empty value has meaning within our
application.

I'm sure that this issue has been seen and address thousands
(millions?) of times... any guidance would be appreciated.