创建一个"other"类别

如果我们想按邮政编码汇总 Evanston 的 311 请求，把所有低频的邮编合并到一个"other"类别会很有用。

下列哪个数值替换查询中的 ???，会得到如下结果？

查询：

SELECT CASE WHEN zipcount < ??? THEN 'other'
       ELSE zip
       END AS zip_recoded,
       sum(zipcount) AS zipsum
  FROM (SELECT zip, count(*) AS zipcount
          FROM evanston311
         GROUP BY zip) AS fullcounts
 GROUP BY zip_recoded
 ORDER BY zipsum DESC;

结果：

zip_recoded    zipsum
60201          19054
60202          11165
null           5528
other          429
60208          255