Allocating ODBC handles

The handle types required for ODBC programs are as follows:

Item Handle type
Environment SQLHENV
Connection SQLHDBC
Statement SQLHSTMT
Descriptor SQLHDESC

To use an ODBC handle

  1. Call the SQLAllocHandle function.

    SQLAllocHandle takes the following parameters:

    • an identifier for the type of item being allocated
    • the handle of the parent item
    • a pointer to the location of the handle to be allocated

      For a full description, see [external link] SQLAllocHandle in the Microsoft ODBC Programmer's Reference.

  2. Use the handle in subsequent function calls.

  3. Free the object using SQLFreeHandle.

    SQLFreeHandle takes the following parameters:

    • an identifier for the type of item being freed
    • the handle of the item being freed

      For a full description, see [external link] SQLFreeHandle in the Microsoft ODBC Programmer's Reference.

Example

The following code fragment allocates and frees an environment handle:

SQLHENV env;
SQLRETURN retcode;
retcode = SQLAllocHandle( 
      SQL_HANDLE_ENV, 
      SQL_NULL_HANDLE, 
      &env ); 
if( retcode == SQL_SUCCESS 
    || retcode == SQL_SUCCESS_WITH_INFO ) {
  // success: application Code here
}
SQLFreeHandle( SQL_HANDLE_ENV, env );

For more information about return codes and error handling, see Handling errors.

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