insert 함수
boolean insert_new_student(char *id, char *name, char *dept, int credits)
delete 함수
boolean delete_by_id(char *table_name, char *id)
/* send SQL query */
if (mysql_query(conn, "SELECT * FROM course WHERE dept_name='Comp. Sci. ' AND credits=3")) {
fprintf(stderr, "%s\n", mysql_error(conn));
exit(1);
}
res = mysql_use_result(conn);
