[笔记]Hive知识汇总

1.如何创建hive表

CREATE TABLE MOD_SWCK_INFO(
       BILL_MONTH          STRING,
       CITY_NAME           STRING,
       CITY_CODE           STRING,
       COUNTY_NAME         STRING,
       COUNTY_CODE         STRING,
       CHN_ID              STRING,
       CHN_NAME            STRING,
       CHN_TYPE            STRING,
       LOGIN_ID            STRING,  
       LOGIN_NAME          STRING,
       DEAL_TYPE           STRING,
       GOODS_TYPE          STRING,
       TERM_BRAND_CODE     STRING,
       TERM_BRAND_NAME     STRING,
       TERM_TYPE_CODE      STRING,
       TERM_TYPE_NAME      STRING,
       CARD_TYPE           STRING,
       CARD_TYPE_NAME      STRING,
       SIM_MEMORY          STRING,
       CARD_VALUE          STRING,
       TERM_ESN            STRING,
       TRADE_ID            STRING,
       USER_ID             STRING,
       DEAL_TIME           STRING,
       OUTBOUND_TIME       STRING     
) 
PARTITIONED BY
       (`YEAR`    STRING,
        `MONTH`   STRING,
        `DAY`     STRING,
        `DB_TYPE` STRING)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '^';

  插入数据:

INSERT OVERWRITE TABLE MOD_SWCK_INFO PARTITION(YEAR,MONTH,DAY,DB_TYPE)
SELECT

ps: 将数据插入表中最好先建立临时表

2.我们在做hive的表的时候，如果我们要保留几位小数，首先想到的就是round函数，但是，如果我们计算的指标数据量很大，那么就会出现科学计数法，往往我们不需要用科学计数法，我们可以用cast( zhibiao as decimal(n,m))       n是总的位数，m是需要保留的小数位数  

3.hive修改 表/分区语句

链接:https://blog.csdn.net/zhangzhongzhong/article/details/65632583

alter table rpt_jh_khzl drop partition(year='2018'，month='12'，day='01')；

alter table rpt_jh_khzl add partition(year='2018'，month='12'，day='01'，db_type='QH') location '2018/12/01/QH';

4.hive修改表中字段的位置

增加字段

ALTER TABLE audit_temp ADD COLUMNS(other STRING);

修改字段位置

 ALTER TABLE audit_temp CHANGE COLUMN other other STRING AFTER hav_coin;

这两步顺序执行