在HIVE中，除了COUNT(*)外，COUNT还可以有很多高级用法。

SELECTtype, count(*), count(DISTINCT u), count(CASE WHEN plat=1 THEN u ELSE NULL END), count(DISTINCT CASE WHEN plat=1 THEN u ELSE NULL END), count(CASE WHEN (type=2 OR type=6) THEN u ELSE NULL END), count(DISTINCT CASE WHEN (type=2 OR type=6) THEN u ELSE NULL END)FROMtWHEREdt in ("2012-1-12-02", "2012-1-12-03")GROUP BYtypeORDER BYtype;

转发:http://athenaxu.blog.163.com/blog/static/205722039201411811440504/