Hive之命令

说明：此博客只记录了一些常见的hql，create/select/insert/update/delete这些基础操作是没有记录的。

select
day -- 时间
,date_add(day,1 - dayofweek(day)) as week_first_day -- 本周第一天_周日
,date_add(day,7 - dayofweek(day)) as week_last_day -- 本周最后一天_周六
,date_add(day,1 - case when dayofweek(day) = 1 then 7 else dayofweek(day) - 1 end) as week_first_day -- 本周第一天_周一
,date_add(day,7 - case when dayofweek(day) = 1 then 7 else dayofweek(day) - 1 end) as week_last_day -- 本周最后一天_周日
,next_day(day,'TU') as next_tuesday -- 当前日期的下个周二
,trunc(day,'MM') as month_first_day -- 当月第一天
,last_day(day) as month_last_day -- 当月最后一天
,to_date(concat(year(day),'-',lpad(ceil(month(day)/3) * 3 -2,2,0),'-01')) as season_first_day -- 当季第一天
,last_day(to_date(concat(year(day),'-',lpad(ceil(month(day)/3) * 3,2,0),'-01'))) as season_last_day -- 当季最后一天
,trunc(day,'YY') as year_first_day -- 当年第一天
,last_day(add_months(trunc(day,'YY'),12)) as year_last_day -- 当年最后一天
,weekofyear(day) as weekofyear -- 当年第几周
,second(day) as second -- 秒钟
,minute(day) as minute -- 分钟
,hour(day) as hour -- 小时
,day(day) as day -- 日期
,month(day) as month -- 月份
,lpad(ceil(month(day)/3),2,0) as season -- 季度
,year(day) as year -- 年份
from (
select '2018-01-02 01:01:01' as day union all
select '2018-02-02 02:03:04' as day union all
select '2018-03-02 03:05:07' as day union all
select '2018-04-02 04:07:10' as day union all
select '2018-05-02 05:09:13' as day union all
select '2018-06-02 06:11:16' as day union all
select '2018-07-02 07:13:19' as day union all
select '2018-08-02 08:15:22' as day union all
select '2018-09-02 09:17:25' as day union all
select '2018-10-02 10:19:28' as day union all
select '2018-11-02 11:21:31' as day union all
select '2018-12-02 12:23:34' as day
) t1
;

select
year('2018-02-27 10:00:00') as year
,month('2018-02-27 10:00:00') as month
,day('2018-02-27 10:00:00') as day
,hour('2018-02-27 10:00:00') as hour
,minute('2018-02-27 10:00:00') as minute
,second('2018-02-27 10:00:00') as second
,weekofyear('2018-02-27 10:00:00') as weekofyear
;
+-------+--------+------+-------+---------+---------+-------------+--+
| year | month | day | hour | minute | second | weekofyear |
+-------+--------+------+-------+---------+---------+-------------+--+
| 2018 | 2 | 27 | 10 | 0 | 0 | 9 |
+-------+--------+------+-------+---------+---------+-------------+--+

-- 获取系统时间
select from_unixtime(unix_timestamp());
select from_unixtime(unix_timestamp(),'yyyy--MM--dd HH:mm:ss') as current_time;
-- 获取当天时间(yyyy-MM-dd)
select current_date;
-- 获取系统时间戳
select unix_timestamp();
-- 时间戳转日期
select from_unixtime(unix_timestamp(),'yyyyMMdd');
-- 日期加减：date_add（时间，增加天数） date_sub（时间，减少天数），返回日期减少天后的日期
select regexp_replace(date_add(FROM_UNIXTIME(UNIX_TIMESTAMP()),-1),'-','');
select regexp_replace(date_sub(FROM_UNIXTIME(UNIX_TIMESTAMP()),1),'-','');

-- 日期差值：datediff(结束日期，开始日期)，返回结束日期减去开始日期的天数。
select datediff(CURRENT_DATE,'2017-01-01') as datediff;

-- 查询当前系统时间(包括毫秒数)
select current_timestamp;
-- 查询当月第几天
select dayofmonth(current_date);
-- 月末
select last_day(current_date);
-- 当月第1天
select date_sub(current_date,dayofmonth(current_date)-1);

-- 查看所有库信息
show database;
-- 进入指定数据库
use {dbName};
-- 查看指定库的所有表
show tables ;
-- 正则表达式过滤表
show tables 'table*';

-- 查看hive表信息
desc formatted {dbName.tabName};
-- 查看hive库信息
describe database extended {dbName};
-- 查询表的某一列
describe {dbName.tabName.fieldName};
-- 查看表结构详情
show create table {dbName.tabName};
-- 查看表的分区
show partitions tablename;

三、字段级

-- 删除hive库以及库中的表
drop database {dbName} CASCADE;
-- hive增加主键
alter table {tabName} set TBLPROPERTIES('PRIMARY_KEY'='field1,field2,field3');
-- 添加字段
alter table {dbName.tabName} add columns(column_1 int,column_2 string);
-- 修改字段名称
alter table {dbName.tabName} change column_1 new_column_1 int;
-- 删除字段(hive暂不支持)
alter table {dbName.tabName} drop columns column_1;
-- 修改字段注释
alter table {dbName.tabName} change column column_1 column_1 string COMMENT '字段注释';

-- 字符串拼接
select concat('c1','c2') as c3;
-- 查看数据库中所有的表
show tables in {dbName};
-- 添加jar包
add jar hdfs://testUDF.jar;
-- 创建临时函数
create temporary function dbName.funName as '{com.libt.testUDF}';
-- 创建永久函数
create function dbName.funName as '{com.libt.testUDF}';

-- 设置执行引擎
set hive.execution.engine=mr;
-- 设置队列
set mapreduce.job.queuename=dev;
--开启动态分区
set hive.exec.dynamic.partition=true;
--允许所有分区为动态分区
set hive.exec.dynamic.partition.mode=nonstrict;

• analyze 普通表
  analyze table dbName.tableName compute statistics;
• analyze 分区表
  analyze table dbName.tableName partition(ds) compute statistics;
• 重新计算元数据
  msck repair table tableName;