MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 21: ODBC API Reference

SQLGetFunctions

Conformance

Version Introduced: ODBC 1.0
Standards Compliance: ISO 92

Summary

SQLGetFunctions returns information about whether a driver supports a specific ODBC function. This function is implemented in the Driver Manager; it can also be implemented in drivers. If a driver implements SQLGetFunctions, the Driver Manager calls the function in the driver. Otherwise, it executes the function itself.

Syntax

SQLRETURN SQLGetFunctions(
     SQLHDBC     ConnectionHandle,
     SQLUSMALLINT     FunctionId,
     SQLUSMALLINT *     SupportedPtr);

Arguments

ConnectionHandle

[Input]
Connection handle.

FunctionId

[Input]
A #define value that identifies the ODBC function of interest; SQL_API_ODBC3_ALL_FUNCTIONS or SQL_API_ALL_FUNCTIONS. SQL_API_ODBC3_ALL_FUNCTIONS is used by an ODBC 3.x application to determine support of ODBC 3.x and earlier functions. SQL_API_ALL_FUNCTIONS is used by an ODBC 2.x application to determine support of ODBC 2.x and earlier functions.

For a list of #define values that identify ODBC functions, see the tables in "Comments."

SupportedPtr

[Output]
If FunctionId identifies a single ODBC function, SupportedPtr points to a single SQLUSMALLINT value that is SQL_TRUE if the specified function is supported by the driver, and SQL_FALSE if it is not supported.

If FunctionId is SQL_API_ODBC3_ALL_FUNCTIONS, SupportedPtr points to a SQLSMALLINT array with a number of elements equal to SQL_API_ODBC3_ALL_FUNCTIONS_SIZE. This array is treated by the Driver Manager as a 4,000-bit bitmap that can be used to determine whether an ODBC 3.x or earlier function is supported. The SQL_FUNC_EXISTS macro is called to determine function support. (See "Comments.") An ODBC 3.x application can call SQLGetFunctions with SQL_API_ODBC3_ALL_FUNCTIONS against either an ODBC 3.x or ODBC 2.x driver.

If FunctionId is SQL_API_ALL_FUNCTIONS, SupportedPtr points to an SQLUSMALLINT array of 100 elements. The array is indexed by #define values used by FunctionId to identify each ODBC function; some elements of the array are unused and reserved for future use. An element is SQL_TRUE if it identifies an ODBC 2.x or earlier function supported by the driver. It is SQL_FALSE if it identifies an ODBC function not supported by the driver or does not identify an ODBC function.

The arrays returned in *SupportedPtr use zero-based indexing.

Returns

SQL_SUCCESS, SQL_SUCCESS_WITH_INFO, SQL_ERROR, or SQL_INVALID_HANDLE.

Diagnostics

When SQLGetFunctions returns SQL_ERROR or SQL_SUCCESS_WITH_INFO, an associated SQLSTATE value can be obtained by calling SQLGetDiagRec with a HandleType of SQL_HANDLE_DBC and a Handle of ConnectionHandle. The following table lists the SQLSTATE values commonly returned by SQLGetFunctions and explains each one in the context of this function; the notation "(DM)" precedes the descriptions of SQLSTATEs returned by the Driver Manager. The return code associated with each SQLSTATE value is SQL_ERROR, unless noted otherwise.

Comments

SQLGetFunctions always returns that SQLGetFunctions, SQLDataSources, and SQLDrivers are supported. It does this because these functions are implemented in the Driver Manager. The Driver Manager will map an ANSI function to the corresponding Unicode function if the Unicode function exists and will map a Unicode function to the corresponding ANSI function if the ANSI function exists. For information about how applications use SQLGetFunctions, see "Interface Conformance Levels" in Chapter 4, "ODBC Fundamentals."

The following is a list of valid values for FunctionId for functions that conform to the ISO 92 standards–compliance level:

The following is a list of valid values for FunctionId for functions conforming to the X/Open standards–compliance level:

The following is a list of valid values for FunctionId for functions conforming to the ODBC standards–compliance level.

[1]   When working with an ODBC 2.x driver, SQLBulkOperations will be returned as supported only if both of the following are true: the ODBC 2.x driver supports SQLSetPos, and the information type SQL_POS_OPERATIONS returns the SQL_POS_ADD bit as set.

SQL_FUNC_EXISTS Macro

The SQL_FUNC_EXISTS(SupportedPtr, FunctionID) macro is used to determine support of ODBC 3.x or earlier functions after SQLGetFunctions has been called with a FunctionId argument of SQL_API_ODBC3_ALL_FUNCTIONS. The application calls SQL_FUNC_EXISTS with the SupportedPtr argument set to the SupportedPtr passed in SQLGetFunctions, and with the FunctionID argument set to the #define for the function. SQL_FUNC_EXISTS returns SQL_TRUE if the function is supported, and SQL_FALSE otherwise.

Note   When working with an ODBC 2.x driver, the ODBC 3.x Driver Manager will return SQL_TRUE for SQLAllocHandle and SQLFreeHandle because SQLAllocHandle is mapped to SQLAllocEnv, SQLAllocConnect, or SQLAllocStmt, and because SQLFreeHandle is mapped to SQLFreeEnv, SQLFreeConnect, or SQLFreeStmt. SQLAllocHandle or SQLFreeHandle with a HandleType argument of SQL_HANDLE_DESC is not supported, however, even though SQL_TRUE is returned for the functions, because there is no ODBC 2.x function to map to in this case.

Code Example

The following two examples show how an application uses SQLGetFunctions to determine if a driver supports SQLTables, SQLColumns, and SQLStatistics. If the driver does not support these functions, the application disconnects from the driver. The first example calls SQLGetFunctions once for each function.

SQLUSMALLINT TablesExists, ColumnsExists, StatisticsExists;

SQLGetFunctions(hdbc, SQL_API_SQLTABLES, &TablesExists);
SQLGetFunctions(hdbc, SQL_API_SQLCOLUMNS, &ColumnsExists);
SQLGetFunctions(hdbc, SQL_API_SQLSTATISTICS, &StatisticsExists);

if (TablesExists && ColumnsExists && StatisticsExists) {

   /* Continue with application */

}

SQLDisconnect(hdbc);

The second example calls SQLGetFunctions a single time and passes it an array in which SQLGetFunctions returns information about all ODBC functions.

#define FUNCTIONS 100

SQLUSMALLINT fExists[FUNCTIONS];

SQLGetFunctions(hdbc, SQL_API_ALL_FUNCTIONS, fExists);

if (fExists[SQL_API_SQLTABLES] &&
   fExists[SQL_API_SQLCOLUMNS] &&
   fExists[SQL_API_SQLSTATISTICS]) {

   /* Continue with application */

}

SQLDisconnect(hdbc);

Related Functions