MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 17: Programming Considerations
The ODBC 3.5 (or higher) Driver Manager supports both ANSI and Unicode versions of all functions that accept pointers to character strings or SQLPOINTER in their arguments. The Unicode functions are implemented as functions (with a suffix of W), not as macros. The ANSI functions (which can be called with or without a suffix of A) are identical to the current ODBC API functions.
Unicode functions that always return or take strings or length arguments are passed as count-of-characters. For functions that return length information for server data, the display size and precision are described in number of characters. When a length (transfer size of the data) could refer to string or nonstring data, the length is described in octet lengths. For example, SQLGetInfoW will still take the length as count-of-bytes, but SQLExecDirectW will use count-of-characters.
The following is a list of the ODBC API functions that support both Unicode (W) and ANSI (A) versions:
| SQLBrowseConnect | SQLGetDiagField |
| SQLColAttribute | SQLGetDiagRec |
| SQLColAttributes | SQLGetInfo |
| SQLColumnPrivileges | SQLGetStmtAttr |
| SQLColumns | SQLNativeSQL |
| SQLConnect | SQLPrepare |
| SQLDataSources | SQLPrimaryKeys |
| SQLDescribeCol | SQLProcedureColumns |
| SQLDriverConnect | SQLProcedures |
| SQLDrivers | SQLSetConnectAttr |
| SQLError | SQLSetConnectOption |
| SQLExecDirect | SQLSetCursorName |
| SQLForeignKeys | SQLSetDescField |
| SQLGetConnectAttr | SQLSetStmtAttr |
| SQLGetConnectOption | SQLSpecialColumns |
| SQLGetCursorName | SQLStatistics |
| SQLGetDescField | SQLTablePrivileges |
| SQLGetDescRec | SQLTables |
The following is a list of the ODBC Installer and ODBC Translator functions that require both Unicode (W) and ANSI (A) versions:
| SQLConfigDataSource | SQLInstallDriver |
| SQLCreateDataSource | SQLInstallDriverManager |
| SQLDataSourceToDriver | SQLInstallODBC |
| SQLDriverToDataSource | SQLRemoveDSNFromINI |
| SQLGetAvailableDrivers | SQLValidDSN |
| SQLGetInstalledDrivers | SQLWriteDSNToINI |
| SQLGetTranslator |
Note Deprecated functions have Unicode-to-ANSI mapping support because the ODBC 3.x Driver Manager supports recompiling ODBC 2.x applications with the UNICODE #define.