External Table in Oracle

From Version 9i Oracle has come with a new feature facilitating us to query directly from the FLAT File. This is know as external tables.
Here are the simple steps for creating external table
1) Create Directory

create or replace directory sv_ext_dir as '/home/svaishya/external_table'

2) Grant access to Directory

grant read, write on directory sv_ext_dir to apps

The user must have a read and write permission the directory('/home/svaishya/external_table' in this case).
3) Create External Table

CREATE TABLE sv_external_Table
(col1 VARCHAR2(50)
,col2 VARCHAR2(50)
)
ORGANIZATION EXTERNAL
( TYPE oracle_loader
DEFAULT DIRECTORY sv_ext_dir
ACCESS PARAMETERS
( FIELDS TERMINATED BY '|' )
LOCATION ('abc.txt')
)

abc.txt is the name of the file that will be located in the path mentioned in the directory sv_ext_dir

4) Place the file in the Directory Path

abc.txt (used in above create table command) is copied the directory.

5) Thats it, query table to extract data.

SELECT * FROM sv_external_table

Everytime the file is updated with new data the data in the table will be automatically refreshed.