Hive基础sql语法(DML)

企业开发 2018-06-24 16:13:08 阅读次数: 2

DML操作(Data Manipulation Language)

参考官方文档： DML文档

  • 因update和delete在Hive中一般用不到，本篇文章不做讲解。本文主要介绍Load和insert操作。
1. LOAD（加载数据）

LOAD作用是加载文件到表中（Loading files into tables）

  • 下面是官网上为我们列出的语法：

    LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]
LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)] [INPUTFORMAT 'inputformat' SERDE 'serde'] (3.0 or later)

  • 1.加载数据到表中时，Hive不做任何转换。加载操作只是把数据拷贝或移动操作，即移动数据文件到Hive表相应的位置。

  • 2.加载的目标可以是一个表，也可以是一个分区。如果表是分区的，则必须通过指定所有分区列的值来指定一个表的分区。

  • 3.filepath可以是一个文件，也可以是一个目录。不管什么情况下，filepath被认为是一个文件集合。

LOCAL：表示输入文件在本地文件系统（Linux），如果没有加LOCAL，hive则会去HDFS上查找该文件。
OVERWRITE：表示如果表中有数据，则先删除数据，再插入新数据，如果没有这个关键词，则直接附加数据到表中。
PARTITION：如果表中存在分区，可以按照分区进行导入。

# 创建一张员工表
hive> create table emp 
    > (empno int, ename string, job string, mgr int, hiredate string, salary double, comm double, deptno int)
    > ROW FORMAT DELIMITED 
    > FIELDS TERMINATED BY '\t' ;
OK
Time taken: 0.651 seconds
# 把本地文件系统中emp.txt导入表
hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' OVERWRITE INTO TABLE emp; 
Loading data to table default.emp
Table default.emp stats: [numFiles=1, numRows=0, totalSize=886, rawDataSize=0]
OK
Time taken: 1.848 seconds
# 查看表数据
hive> select * from emp;
OK
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
# 不用OVERWRITE关键字
hive>  LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt'  INTO TABLE emp;
# 再次查看
hive> select * from emp;
OK
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
Time taken: 0.137 seconds, Fetched: 28 row(s)
# 再次OVERWRITE覆盖导入
hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' OVERWRITE INTO TABLE emp; 
# 发现数据被覆盖了
hive> select * from emp;
OK
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
Time taken: 0.164 seconds, Fetched: 14 row(s)
2. insert into到表（Inserting data into Hive Tables from queries）
  • 下面是官网上为我们列出的语法：
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_statement
INSERT 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_statement
INSERT 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;

官网又给我们列出一大堆语法，看着就很可怕，但是仔细整理后再来看看你会发现并没有什么，下面对其进行分析：

  • 1 标准语法（Standard syntax）：INSERT OVERWRITE TABLE tablename1 select_statement1 FROM from_statement; 其实就是一个简单的插入语句。
  • 2.可以使用PARTITION 关键字，进行分区插入。
  • 3.OVERWRITE是否选择覆盖。

  • 4 使用插入语法会跑mr作业。

  • 5 multiple inserts：代表多行插入。

  • 6 dynamic partition inserts：动态分区插入。

注：这里有两种插语法，也就是加上OVERWRITE关键字和不加的区别。

# insert overwrite
hive> insert overwrite table emp2 select * from emp;
Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
Total jobs = 3
Launching Job 1 out of 3
...
OK
Time taken: 19.554 seconds
hive> select * from emp2;
OK
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
Time taken: 0.143 seconds, Fetched: 14 row(s)

# insert追加
hive> insert into table emp2 select * from emp;
Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
Total jobs = 3
...
OK
Time taken: 18.539 seconds
hive> select * from emp2;
OK
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
Time taken: 0.132 seconds, Fetched: 28 row(s)
  • Inserting values into tables（手动插入一条或多条记录，会跑mr作业 不常用）
  • 官方用法： 
    INSERT INTO TABLE tablename [PARTITION (partcol1[=val1], partcol2[=val2] ...)] VALUES values_row [, values_row ...]
hive> create table stu(
    > id int,
    > name string
    > )
    >  ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t';
OK
Time taken: 0.253 seconds
hive> insert into table stu values (1,"zhangsan");
Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
Total jobs = 3
...
OK
Time taken: 16.589 seconds
hive> select * from stu;
OK
1       zhangsan
Time taken: 0.123 seconds, Fetched: 1 row(s)
3. 数据导出（Writing data into the filesystem from queries）

查询结果可以通过语句插入文件系统中：

  • 下面是官网上为我们列出的语法： 
    
Standard syntax:（标准语法）
INSERT OVERWRITE [LOCAL] DIRECTORY directory1
[ROW FORMAT row_format] [STORED AS file_format] (Note: Only available starting with Hive 0.11.0)
SELECT ... FROM ...

Hive extension (multiple inserts):（导出多条记录）
FROM from_statement
INSERT OVERWRITE [LOCAL] DIRECTORY directory1 select_statement1
[INSERT OVERWRITE [LOCAL] DIRECTORY directory2 select_statement2] ...

row_format
: DELIMITED [FIELDS TERMINATED BY char [ESCAPED BY char]] [COLLECTION ITEMS TERMINATED BY char]
[MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char]
[NULL DEFINED AS char] (Note: Only available starting with Hive 0.13)

**LOCAL**：加上LOCAL关键字代表导入本地系统，不加默认导入HDFS； 
**STORED AS**:可以指定存储格式。

```shell
hive> insert overwrite local directory '/home/hadoop/stu' ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t' select * from stu;
Query ID = hadoop_20180624153131_97271014-abcf-4e70-b318-7de85d27c97f
Total jobs = 1
...
OK
Time taken: 15.09 seconds
# 结果
[hadoop@hadoop000 stu]$ pwd
/home/hadoop/stu
[hadoop@hadoop000 stu]$ cat 000000_0 
1       zhangsan

# 导出多条记录
hive> from emp
    > INSERT OVERWRITE  LOCAL DIRECTORY '/home/hadoop/tmp/hivetmp1'
    > ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
    > select empno, ename  
    > INSERT OVERWRITE  LOCAL DIRECTORY '/home/hadoop/tmp/hivetmp2'
    > ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
    > select ename;
Query ID = hadoop_20180624153131_97271014-abcf-4e70-b318-7de85d27c97f
Total jobs = 1
...
OK
Time taken: 16.261 seconds
# 结果
[hadoop@hadoop000 tmp]$ cd hivetmp1
[hadoop@hadoop000 hivetmp1]$ ll
total 4
-rw-r--r-- 1 hadoop hadoop 154 Jun 24 15:39 000000_0
[hadoop@hadoop000 hivetmp1]$ cat 000000_0 
7369    SMITH
7499    ALLEN
7521    WARD
7566    JONES
7654    MARTIN
7698    BLAKE
7782    CLARK
7788    SCOTT
7839    KING
7844    TURNER
7876    ADAMS
7900    JAMES
7902    FORD
7934    MILLER
[hadoop@hadoop000 hivetmp1]$ cd ..
[hadoop@hadoop000 tmp]$ cd hivetmp2
[hadoop@hadoop000 hivetmp2]$ cat 000000_0 
SMITH
ALLEN
WARD
JONES
MARTIN
BLAKE
CLARK
SCOTT
KING
TURNER
ADAMS
JAMES
FORD
MILLER

参考： https://blog.csdn.net/yu0_zhang0/article/details/79007784

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