大数据技术_Hive_总结
查看数据库
0: jdbc:hive2://hadoop102:10000> show databases;
0: jdbc:hive2://hadoop102:10000> show databases like "m.*";
0: jdbc:hive2://hadoop102:10000> show databases like 'm.*';
注： describe 的简写就是 desc ，databases 关键字必须有。
0: jdbc:hive2://hadoop102:10000> show databases;
+----------------+--+
| database_name |
+----------------+--+
| default |
| financials |
| mydb1 |
| myhivedb |
+----------------+--+
4 rows selected (0.031 seconds)
0: jdbc:hive2://hadoop102:10000> show databases like "m.*";
+----------------+--+
| database_name |
+----------------+--+
| mydb1 |
| myhivedb |
+----------------+--+
2 rows selected (0.054 seconds)
0: jdbc:hive2://hadoop102:10000> show databases like 'm.*';
+----------------+--+
| database_name |
+----------------+--+
| mydb1 |
| myhivedb |
+----------------+--+
2 rows selected (0.023 seconds)
查看数据库的时候可以使用通配符（Like）或者正则表达式（RLike），关键字必须有，通配符或者正则表达式用单引号双引号都可以。
查看数据库的详细信息：
0: jdbc:hive2://hadoop102:10000> desc database myhivedb;
0: jdbc:hive2://hadoop102:10000> describe database myhivedb;
0: jdbc:hive2://hadoop102:10000> describe database extended myhivedb;
注：关键字 database 必须有。
0: jdbc:hive2://hadoop102:10000> desc myhivedb;
Error: Error while compiling statement: FAILED: SemanticException [Error 10001]: Table not found myhivedb (state=42S02,code=10001)
0: jdbc:hive2://hadoop102:10000> desc database myhivedb;
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
| db_name | comment | location | owner_name | owner_type | parameters |
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
| myhivedb | | hdfs://hadoop102:9000/user/hive/warehouse/myhivedb.db | atguigu | USER | |
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
1 row selected (0.031 seconds)
0: jdbc:hive2://hadoop102:10000> describe database myhivedb;
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
| db_name | comment | location | owner_name | owner_type | parameters |
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
| myhivedb | | hdfs://hadoop102:9000/user/hive/warehouse/myhivedb.db | atguigu | USER | |
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
1 row selected (0.034 seconds)
0: jdbc:hive2://hadoop102:10000> describe database extended myhivedb;
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
| db_name | comment | location | owner_name | owner_type | parameters |
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
| myhivedb | | hdfs://hadoop102:9000/user/hive/warehouse/myhivedb.db | atguigu | USER | |
+-----------+----------+--------------------------------------------------------+-------------+-------------+-------------+--+
1 row selected (0.029 seconds)
查看表
0: jdbc:hive2://hadoop102:10000> use myhivedb;
0: jdbc:hive2://hadoop102:10000> show tables;
0: jdbc:hive2://hadoop102:10000> show tables in myhivedb;
0: jdbc:hive2://hadoop102:10000> show tables;
0: jdbc:hive2://hadoop102:10000> show tables like "m.*";
0: jdbc:hive2://hadoop102:10000> show tables like 'm.*';
0: jdbc:hive2://hadoop102:10000> show tables 'm.*';
和查询数据库不同，这里的 like 可加可不加，但是查询数据的时候必须加（ show databases like "m.*";）
0: jdbc:hive2://hadoop102:10000> desc employess;
0: jdbc:hive2://hadoop102:10000> desc formatted employess;
0: jdbc:hive2://hadoop102:10000>desc extended employess;
查询表的类型（Table Type）等详细信息需要使用 desc formatted employess ，使用 desc extended employess 会看不清楚。
0: jdbc:hive2://hadoop102:10000> desc employess.salary;
可以单独查一个属性
0: jdbc:hive2://hadoop102:10000> desc employess.salary;
+-----------+------------+--------------------+--+
| col_name | data_type | comment |
+-----------+------------+--------------------+--+
| salary | float | from deserializer |
+-----------+------------+--------------------+--+
1 row selected (0.1 seconds)
0: jdbc:hive2://hadoop102:10000> use myhivedb;
No rows affected (0.03 seconds)
0: jdbc:hive2://hadoop102:10000> show tables;
+------------+--+
| tab_name |
+------------+--+
| employess |
| mytable |
| mytable2 |
| some_data |
+------------+--+
4 rows selected (0.037 seconds)
0: jdbc:hive2://hadoop102:10000> show tables in myhivedb;
+------------+--+
| tab_name |
+------------+--+
| employess |
| mytable |
| mytable2 |
| some_data |
+------------+--+
4 rows selected (0.035 seconds)
0: jdbc:hive2://hadoop102:10000>
0: jdbc:hive2://hadoop102:10000> desc employess;
+---------------+---------------------------------------------------------+----------+--+
| col_name | data_type | comment |
+---------------+---------------------------------------------------------+----------+--+
| name | string | |
| salary | float | |
| subordinates | array | |
| deductions | map | |
| address | struct | |
+---------------+---------------------------------------------------------+----------+--+
5 rows selected (0.071 seconds)
0: jdbc:hive2://hadoop102:10000> desc formatted employess;
+-------------------------------+------------------------------------------------------------------+-----------------------+--+
| col_name | data_type | comment |
+-------------------------------+------------------------------------------------------------------+-----------------------+--+
| # col_name | data_type | comment |
| | NULL | NULL |
| name | string | |
| salary | float | |
| subordinates | array | |
| deductions | map | |
| address | struct | |
| | NULL | NULL |
| # Detailed Table Information | NULL | NULL |
| Database: | myhivedb | NULL |
| Owner: | atguigu | NULL |
| CreateTime: | Sat Apr 20 21:31:53 CST 2019 | NULL |
| LastAccessTime: | UNKNOWN | NULL |
| Protect Mode: | None | NULL |
| Retention: | 0 | NULL |
| Location: | hdfs://hadoop102:9000/user/hive/warehouse/myhivedb.db/employess | NULL |
| Table Type: | MANAGED_TABLE | NULL |
| Table Parameters: | NULL | NULL |
| | transient_lastDdlTime | 1555767113 |
| | NULL | NULL |
| # Storage Information | NULL | NULL |
| SerDe Library: | org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe | NULL |
| InputFormat: | org.apache.hadoop.mapred.TextInputFormat | NULL |
| OutputFormat: | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat | NULL |
| Compressed: | No | NULL |
| Num Buckets: | -1 | NULL |
| Bucket Columns: | [] | NULL |
| Sort Columns: | [] | NULL |
| Storage Desc Params: | NULL | NULL |
| | serialization.format | 1 |
+-------------------------------+------------------------------------------------------------------+-----------------------+--+
30 rows selected (0.075 seconds)
0: jdbc:hive2://hadoop102:10000>