The sqlite3_stmt_busy(S) interface returns true (non-zero) if the prepared statement S has been stepped at least once using sqlite3_step(S) but has not run to completion and/or has not been reset using sqlite3_reset(S). The sqlite3_stmt_busy(S) interface returns false if S is a NULL pointer. If S is not a NULL pointer and is not a pointer to a valid prepared statement object, then the behavior is undefined and probably undesirable.
This interface can be used in combination sqlite3_next_stmt() to locate all prepared statements associated with a database connection that are in need of being reset. This can be used, for example, in diagnostic routines to search for prepared statements that are holding a transaction open.