【1】先根据表中数据计算出需要的值，存储在临时表里面，比如计算日活跃度的语句：
with tbl_dau as ( select 'dau' as name, count(distinct deviceid) as cnt from ( select deviceid from src_huidu_zl.event3 where hdfs_par = '20170108' union all select deviceid from src_huidu_zl.page3 where hdfs_par = '20170108' ) as tmp ) w
