External table of Dameng database

An external table is a table that does not exist in the database. By providing Damon with metadata that describes external tables, we can access an operating system file as if it were a read-only database table, as if the data were stored in a normal database table. External tables are an extension of database tables.

The process of creating a simple external table of dreams:

1. Assume that external data is in test.txt

[dmdba@localhost ~] $cat test.txt

1,2,3

4,5,6

two。 Write the control file test.ctl of the external table

[dmdba@localhost ~] $cat test.ctl

LOAD DATA

INFILE'/ home/dmdba/test.txt'

INTO TABLE TEST

FIELDS','

3. Create external table test

SQL > create external table test (C1 int,c2 int,c3 int) from'/ home/dmdba/test.ctl'

4. Validate external table data

SQL > select * from test

Line number C1 C2 C3

1 1 2 3

2 4 5 6