See these pages for more details about Apache Hive:
https://cwiki.apache.org/confluence/display/Hive/GettingStarted
https://cwiki.apache.org/confluence/display/Hive/LanguageManual
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF

See: https://cwiki.apache.org/confluence/display/Hive/Managed+vs.+External+Tables

• Internal (managed) Table: Hive manage both the metadata and the data of the table.
  If a managed table is dropped then the table data and its metadata are deleted.
  The data of a managed table (for a specific database DATABASE-NAME.db) is stored under the hive.metastore.warehouse.dir directory (default: /hive/warehouse/).
  
  

  CREATE TABLE test_internal_table (field1 INT, field2 STRING);

  
  
• External Table: Hive manage only the metadata of the table while the data is located into a location specified when the table is created.
  If an external table is dropped then only the table metadata is deleted.
  
  

  CREATE EXTERNAL TABLE test_external_table (field1 INT, field2 STRING) LOCATION 'hdfs://localhost:8020/test_db/test_external_table';

  
  

You can use the command DESCRIBE FORMATTED table_name to identify if a table is an internal (managed) or an external table.
The command displays MANAGED_TABLE for internal table type and EXTERNAL_TABLE for external table type.

Describe internal tables:

hive> describe formatted test_internal_table;
OK
# col_name                data_type               comment
field1                  int
field2                  string

# Detailed Table Information
Database:               default
OwnerType:              USER
Owner:                  hive
CreateTime:             Sun Dec 30 10:58:22 EDT 2018
LastAccessTime:         UNKNOWN
Retention:              0
Location:               hdfs://localhost:8020/hive/warehouse/test_internal_table
Table Type:             MANAGED_TABLE
Table Parameters:
    COLUMN_STATS_ACCURATE    {\"BASIC_STATS\":\"true\",\"COLUMN_STATS\":{\"field1\":\"true\",\"field2\":\"true\"}}
    bucketing_version       2
    numFiles                0
    numRows                 0
    rawDataSize             0
    totalSize               0
    transient_lastDdlTime    1559487502

# Storage Information
SerDe Library:          org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
InputFormat:            org.apache.hadoop.mapred.TextInputFormat
OutputFormat:           org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
Compressed:             No
Num Buckets:            -1
Bucket Columns:         []
Sort Columns:           []
Storage Desc Params:
    serialization.format    1
Time taken: 0.084 seconds, Fetched: 32 row(s)

Describe external tables:

hive> describe formatted test_external_table;
OK
# col_name                data_type               comment
field1                  int
field2                  string

# Detailed Table Information
Database:               test
OwnerType:              USER
Owner:                  hive
CreateTime:             Sun Dec 30 10:58:22 EDT 2018
LastAccessTime:         UNKNOWN
Retention:              0
Location:               hdfs://localhost:8020/test_external_tables
Table Type:             EXTERNAL_TABLE
Table Parameters:
    EXTERNAL                TRUE
    bucketing_version       2
    numFiles                0
    totalSize               0
    transient_lastDdlTime    1559487888

# Storage Information
SerDe Library:          org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
InputFormat:            org.apache.hadoop.mapred.TextInputFormat
OutputFormat:           org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
Compressed:             No
Num Buckets:            -1
Bucket Columns:         []
Sort Columns:           []
Storage Desc Params:
    serialization.format    1
Time taken: 0.045 seconds, Fetched: 30 row(s)

See these pages for more details about supported file formats:
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL

Create Table statement:

CREATE TABLE table_name
  [(col_name data_type [COMMENT col_comment], ... [constraint_specification])]
   [STORED AS file_format]
  ]

Supported file formats:

TEXTFILE    -- (Default, depending on hive.default.fileformat configuration)
ORC         -- (Note: Available in Hive 0.11.0 and later)
PARQUET     -- (Note: Available in Hive 0.13.0 and later)
AVRO        -- (Note: Available in Hive 0.14.0 and later)
JSONFILE    -- (Note: Available in Hive 4.0.0 and later)
RCFILE      -- (Note: Available in Hive 0.6.0 and later)

Example: ORC Table

CREATE EXTERNAL TABLE test_external_table (field1 INT, field2 STRING) STORED AS ORC;

Create HDFS location:

$ su - hadoop
$ hdfs dfs -mkdir hdfs://localhost:8020/test_db
$ hdfs dfs -chown hive hdfs://localhost:8020/test_db

Switch to "hive" user:

$ su - hive

Create Hive database:

$ hive
> create database test_db;
> exit;

Define Hive tables:

$ vi ~/test_db.hql
CREATE EXTERNAL TABLE test_table_1 (field1 INT, field2 STRING) STORED AS ORC location 'hdfs://localhost:8020/test_db/test_table_1';
CREATE EXTERNAL TABLE test_table_2 (field1 INT, field2 STRING) STORED AS ORC location 'hdfs://localhost:8020/test_db/test_table_2';

Create Hive tables (using hive command line):

$ hive --database test_db -f ~/test_db.hql

Create Hive tables (using beeline command line):

$ beeline
Beeline version 3.1.2 by Apache Hive

beeline> !connect jdbc:hive2://localhost:10000
Enter username for jdbc:hive2://localhost:10000: hive
Enter password for jdbc:hive2://localhost:10000: ****

0: jdbc:hive2://localhost:10000> create database test;

0: jdbc:hive2://localhost:10000> use test;

0: jdbc:hive2://localhost:10000> !run /home/hive/test_db.hql
>>>  CREATE EXTERNAL TABLE test_table_1 (field1 INT, field2 STRING) STORED AS ORC;
>>>  CREATE EXTERNAL TABLE test_table_2 (field1 INT, field2 STRING) STORED AS ORC;

0: jdbc:hive2://localhost:10000> show tables;
+----------------+
|    tab_name    |
+----------------+
| test_table_1  |
| test_table_2  |
+----------------+

Validate Hive database and tables:

$ hdfs dfs -ls hdfs://localhost:8020/hive/warehouse/test_db.db
$ hdfs dfs -ls hdfs://localhost:8020/test_db

Drop Hive database (metadata):

$ hive
> drop database test_db cascade;
> exit;

Drop Hive database (data):

#$ hdfs dfs -rm -r hdfs://localhost:8020/hive/warehouse/test_db.db -- will be deleted when you drop the database
$ hdfs dfs -rm -r hdfs://localhost:8020/test_db