SQLGetTypeInfo
The SQL Native Client ODBC driver reports the additional column USERTYPE in the result set of SQLGetTypeInfo. USERTYPE reports the DB-Library data type definition and is useful to developers porting existing DB-Library applications to ODBC.
SQL Server treats identity as an attribute, whereas ODBC treats it as a data type. To resolve this mismatch, SQLGetTypeInfo returns the data types: intidentity, smallintidentity, tinyintidentity, decimalidentity, and numericidentity. The SQLGetTypeInfo result set column AUTO_UNIQUE_VALUE reports the value TRUE for these data types.
For varchar, nvarchar and varbinary, the SQL Native Client ODBC driver continues to report 8000, 4000 and 8000 respectively for the COLUMN_SIZE value, even though it is actually unlimited. This is to ensure backward compatibility.
For the xml data type, the SQL Native Client ODBC driver reports SQL_SS_LENGTH_UNLIMITED for COLUMN_SIZE to denote unlimited size.
See Also
Concepts
ODBC API Implementation Details