HIVE SQL 实践

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1. select语句

1.1 简单查询

注：最好不要使用 select *

select * from test.imsiBackFill where date_id = 20180920 and hour = 10 limit 10;

1.2 统计行数

select count(1) from test.imsiBackFill where date_id = 20180920 and hour = 10;

#和直接查看HDFS文件结果是一样的
hadoop fs -cat hdfs://mace:9000/user/hive/warehouse/test.db/imsibackfill/date_id=20180920/hour=10/*|wc -l

2.group by

2.1 通过 group by 实现去重统计

select count(1) from (select enodebid from test.imsiBackFill where date_id = 20180920 and hour = 10 group by enodebid) a;