MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 4: ODBC Fundamentals

Type Identifiers

To describe SQL and C data types, ODBC defines two sets of type identifiers. A type identifier describes the type of an SQL column or a C buffer. It is a #define value and is generally passed as a function argument or returned in metadata. For example, the following call to SQLBindParameter binds a variable of type SQL_DATE_STRUCT to a date parameter in an SQL statement. The C type identifier SQL_C_TYPE_DATE specifies the type of the Date variable, and the SQL type identifier SQL_TYPE_DATE specifies the type of the dynamic parameter.

SQL_DATE_STRUCT Date;
SQLINTEGER  DateInd = 0;
SQLBindParameter(hstmt, 1, SQL_PARAM_INPUT, SQL_C_TYPE_DATE, SQL_TYPE_DATE, 0, 0,
                  &Date, 0, &DateInd);