ODBC 64-bit Windows and Linux Considerations

Identify header files and data types when using the ODBC driver in an IBM® i Access environment.

The IBM i Access ODBC driver implements support for 64-bit ODBC APIs. In general, the support is implemented as defined in the ODBC header files that are provided by Microsoft for Windows environments and unixODBC for Linux environments. When you write code to call the ODBC APIs, refer to the appropriate ODBC header file for the function prototype. The header files are as follows:

sql.h
sqlext.h
sqltypes.h
sqlucode.h

Inherent differences between Windows, Linux, and 64-bit include the following:

In 64-bit Linux environments, the size of a long C/C++ type is 8 bytes. In other environments, including 64-bit Windows, the size of the long type is 4 bytes.
In 32-bit environments, the size of a pointer is 4 bytes. In 64-bit environments, the size of a pointer is 8 bytes.
Some of the ODBC APIs have parameters that are pointers. In some cases, these pointers are used to pass data of different sizes between the application and the driver. In 64-bit implementations, there are some changes where the size of data passed this way was changed from being 4-byte values to 8-byte values.

Some common C/C++ types and the size of each are listed in the following table.

Table 1. Common C/C++ types and the size of each
C/C++ Type	Linux 64-bit	Windows 64-bit	Linux 32-bit	Windows 32-bit
int	4	4	4	4
long	8	4	4	4
long long	8	Not defined	8	Not defined
LONG LONG	Not defined	8	Not defined	Not defined
pointer size	8	8	4	4
INT32	Not defined 4¹	4	Not defined 4¹	4
INT64	Not defined 8¹	8	Not defined 8¹	8
SQLSMALLINT	2	2	2	2
SQLINTEGER	4	4	4	4
SQLLEN	8	8	4	4
SQLSETPOSIROW	8	8	2	2
SQLROWCOUNT	8	Not defined	4	4
SQLROWSETSIZE	4	Not defined	4	4
SQLROWOFFSET	8	Not defined	4	4
SQLPOINTER	8	8	4	4
UINT_PTR	Not defined 8¹	8	Not defined 4¹	4
DWORD	Not defined 4¹	4	Not defined 4¹	4
SDWORD	Not defined 4¹	4	Not defined 4¹	4
ULONG_PTR	Not defined 8¹	8	Not defined 4¹	4
SQLHANDLE	8	8	4	4
SQLHDESC	8	8	4	4

Note: 1. This type is not defined in a standard header file. It is defined in the toolkit that is provided with the Linux Application Package product.

Options for the ODBC APIs listed below result in different behavior by the 32-bit and 64-bit ODBC drivers for parameter pointer data. Generally, the 64-bit ODBC drivers treat parameter pointer data as 8 byte (64-bit) values, unless otherwise noted.

SQLGetConnectAttr: SQL_ATTR_QUIET_MODE

SQLGetConnectOption (This API is mapped to SQLGetConnectAttr by the ODBC driver manager.): SQL_ATTR_QUIET_MODE

SQLGetDescField: SQL_DESC_ARRAY_SIZE

SQLGetDiagField: SQL_DIAG_CURSOR_ROW_COUNT; SQL_DIAG_ROW_COUNT; SQL_DIAG_ROW_NUMBER

SQLGetInfo (These options are all handled by the ODBC driver manager.): SQL_DRIVER_HENV; SQL_DRIVER_HDBC; SQL_DRIVER_HLIB; SQL_DRIVER_HSTMT; SQL_DRIVER_HDESC

SQLGetStmtAttr: SQL_ATTR_APP_PARAM_DESC; SQL_ATTR_APP_ROW_DESC; SQL_ATTR_IMP_PARAM_DESC; SQL_ATTR_IMP_ROW_DESC; SQL_ATTR_MAX_LENGTH; SQL_ATTR_MAX_ROWS; SQL_ATTR_PARAM_BIND_OFFSET_PTR; SQL_ATTR_ROW_ARRAY_SIZE; SQL_ATTR_ROW_BIND_OFFSET_PTR; SQL_ATTR_ROW_NUMBER; SQL_ATTR_ROWS_FETCHED_PTR; SQL_ATTR_KEYSET_SIZE

SQLGetStmtOption (This API is mapped to SQLGetStmtAttr by the ODBC driver manager.): SQL_MAX_LENGTH; SQL_MAX_ROWS; SQL_ROWSET_SIZE; SQL_KEYSET_SIZE

SQLSetConnectAttr: SQL_ATTR_QUIET_MODE

SQLSetConnectOption (This API is mapped to SQLSetConnectAttr by the ODBC driver manager.): SQL_ATTR_QUIET_MODE

SQLSetDescField: SQL_DESC_ARRAY_SIZE

SQLSetStmtAttr: SQL_ATTR_APP_PARAM_DESC; SQL_ATTR_APP_ROW_DESC; SQL_ATTR_IMP_PARAM_DESC; SQL_ATTR_IMP_ROW_DESC; SQL_ATTR_MAX_LENGTH; SQL_ATTR_MAX_ROWS; SQL_ATTR_PARAM_BIND_OFFSET_PTR; SQL_ATTR_ROW_ARRAY_SIZE; SQL_ATTR_ROW_BIND_OFFSET_PTR; SQL_ATTR_ROW_NUMBER; SQL_ATTR_ROWS_FETCHED_PTR; SQL_ATTR_KEYSET_SIZE

SQLSetConnectAttr: SQL_MAX_LENGTH; SQL_MAX_ROWS; SQL_ROWSET_SIZE; SQL_KEYSET_SIZE