[hadoop]hive语法（十二）

一、创建数据库

create database hive;

二、创建表

1. 创建员工表
   

   create table t_emp (id int,name string,age int,dept_name string)ROW FORMAT DELIMITED   FIELDS TERMINATED BY ',';

   
   
2. 创建员工文件 emp.txt
   

   1,张三,30,销售部2,李四,31,市场部3,王五,32,研发部4,孙六,33,行政部

3. 导入数据
   

   LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]

   LOAD DATA LOCAL INPATH '/root/emp.txt' INTO TABLE t_emp;

4. 查询员工总数
   

   hive> select count(*) from t_emp;Query ID = root_20160531150116_fa9fcc80-eb98-4e84-ba50-646e4e56d9aaTotal jobs = 1Launching Job 1 out of 1Number of reduce tasks determined at compile time: 1In order to change the average load for a reducer (in bytes):  set hive.exec.reducers.bytes.per.reducer=<number>In order to limit the maximum number of reducers:  set hive.exec.reducers.max=<number>In order to set a constant number of reducers:  set mapreduce.job.reduces=<span style="font-family: Arial, Helvetica, sans-serif;"><number></span>Starting Job = job_1464666884311_0002, Tracking URL = http://node1:8088/proxy/application_1464666884311_0002/Kill Command = /home/hadoop-2.5/bin/hadoop job  -kill job_1464666884311_0002Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 12016-05-31 15:03:09,162 Stage-1 map = 0%,  reduce = 0%2016-05-31 15:04:09,510 Stage-1 map = 0%,  reduce = 0%2016-05-31 15:04:39,292 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 16.43 sec2016-05-31 15:05:39,300 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 16.43 sec2016-05-31 15:05:46,423 Stage-1 map = 100%,  reduce = 67%, Cumulative CPU 19.93 sec2016-05-31 15:05:49,925 Stage-1 map = 100%,  reduce = 100%, Cumulative CPU 23.47 secMapReduce Total cumulative CPU time: 23 seconds 470 msecEnded Job = job_1464666884311_0002MapReduce Jobs Launched: Stage-Stage-1: Map: 1  Reduce: 1   Cumulative CPU: 25.84 sec   HDFS Read: 6793 HDFS Write: 2 SUCCESSTotal MapReduce CPU Time Spent: 25 seconds 840 msecOK4Time taken: 281.847 seconds, Fetched: 1 row(s)

   
   

三、数据类型

参考文档：https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Types

四、导入数据 LOAD

1. LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]

   LOCAL：导入本地数据
   filepath: 相对路径project/data1、绝对路径/user/hive/project/data1、完整url hdfs://namenode:9000/user/hive/project/data1等
   OVERWRITE: 覆盖文件
   PARTITION: 分区，即按名称保存数据的文件夹

五、插入数据 INSERT

Standard syntax:INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1 FROM from_statement;INSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1 FROM from_statement; Hive extension (multiple inserts):FROM from_statementINSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1[INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2][INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2] ...;FROM from_statementINSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1[INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2][INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2] ...; Hive extension (dynamic partition inserts):INSERT OVERWRITE TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement;INSERT INTO TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement;

例如：

1. hive> insert into table t_emp values (5,'xiaoming',12,'hr'),(7,'xiaohong',13,'manager');

   
2. 创建数据库
   

   hive> create table t_emp_1 (    > name varchar(50),    > dname varchar(50));

   插入数据到t_emp_1
   

   hive> insert into t_emp_1 select name, dept_name from t_emp group dept_name;

   

六、导出 Export

EXPORT TABLE tablename [PARTITION (part_column="value"[, ...])]  TO 'export_target_path' [ FOR replication('eventid') ]

hive> export table t_emp to '/usr/file/emp.txt';

七、导入 Import

IMPORT [[EXTERNAL] TABLE new_or_original_tablename [PARTITION (part_column="value"[, ...])]]  FROM 'source_path'  [LOCATION 'import_target_path']

Hive官方dml详细文档：

https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML#LanguageManualDML-InsertingdataintoHiveTablesfromqueries