Create External Table in Oracle: Guide

You can create an external table in Oracle by following these steps:

1. Firstly, it is important to ensure that the database user has the permission to create tables, as well as access external files.
2. Create an external table using the CREATE TABLE statement, with the following syntax:

CREATE TABLE external_table_name
(
  column1 data_type,
  column2 data_type,
  ...
)
ORGANIZATION EXTERNAL
(
  TYPE ORACLE_LOADER
  DEFAULT DIRECTORY directory_name
  ACCESS PARAMETERS
  (
    RECORDS DELIMITED BY NEWLINE
    FIELDS TERMINATED BY ','
    LOCATION ('external_file_name')
  )
)
REJECT LIMIT UNLIMITED;

In this case, external_table_name is the name of the external table created, column1 and column2 are the column names and data types of the external table, directory_name is the name of the directory where the external files are located, and external_file_name is the name of the external file.

1. In the ACCESS PARAMETERS clause, you can configure parameters such as the format of external files and the delimiter of data.
2. When creating an external table, it is important to ensure that the path and format of the external files are consistent with what is specified in the ACCESS PARAMETERS.
3. After creating an external table, you can use a SELECT statement to query the data in the external table, which is dynamically loaded from external files.
4. If you need to delete an external table, you can use the DROP TABLE statement to delete the external table.