When an application and/or process has completed operations with the database, it must release resources by closing the open files and disconnecting from the database engine.
Below is the code for Done():
/*
* Done()
*
* This function handles the housekeeping of closing connection and
* freeing of associated memory
*/
void Done(void)
{
RETCODE rc;
printf("DONE\n");
/* free statement handle */
if ((rc = SQLFreeHandle(SQL_HANDLE_STMT, hStmt)) != SQL_SUCCESS)
Handle_Error(SQL_HANDLE_DBC, hDbc, "SQLFreeHandle(SQL_HANDLE_STMT)");
/* disconnect from server */
printf("\tLogout...\n");
if ((rc = SQLDisconnect(hDbc)) != SQL_SUCCESS)
Handle_Error(SQL_HANDLE_DBC, hDbc, "SQLDisconnect()");
/* free connection handle */
if ((rc = SQLFreeHandle(SQL_HANDLE_DBC, hDbc)) != SQL_SUCCESS)
Handle_Error(SQL_HANDLE_ENV, hEnv, "SQLFreeHandle(SQL_HANDLE_DBC)");
/* free environment handle */
if ((rc = SQLFreeHandle(SQL_HANDLE_ENV, hEnv)) != SQL_SUCCESS)
Handle_Error(0, NULL, "SQLFreeHandle(SQL_HANDLE_ENV)");
}