如何避免重复的子查询？

Question

我正在使用MySql，这是我当前作业的例子：

SELECT a.name, SUM(a.points), (REPEATING_SUBQUERY)
FROM table_1 AS a
GROUP BY a.name
HAVING SUM(a.points) > (REPEATING_SUBQUERY)
OR (REPEATING_SUBQUERY) IS NULL

无论如何都要将'REPEATING_SUBQUERY'设置为参数并加快处理时间？

谢谢！