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Oracle has been enhancing "external table" features in each release .
Here is one of my post describing the support for wildcard characters in the file location.
http://mfzahirdba.blogspot.com/2015/07/external-table-enhancements-in-oracle.html
There were few external table enhancements in Oracle 18c.
One of them is that you do not need to create table first and then reference that external table in your query.
In Oracle 18c and later , I can define the external table definition inline and access the files without defining the external table.
Let us use the same example files in http://mfzahirdba.blogspot.com/2015/07/external-table-enhancements-in-oracle.html
Here is an example .
Sign on and create directory and grant the access to regular user ( in our case , zahir).
SQL> create directory EX_TAB_DIR as 'c:\datadumps\';
Directory created.
SQL> grant read , write , execute on directory EX_TAB_DIR to zahir;
Grant succeeded.
Sign on to the database with the user account.
SQL> show user
USER is "ZAHIR"
SQL> ho dir c:\datadumps
Volume in drive C has no label.
Volume Serial Number is E247-41EF
Directory of c:\datadumps
04/21/2020 05:09 PM
04/21/2020 05:09 PM
04/21/2020 04:52 PM 28 emp1.txt
04/21/2020 04:52 PM 25 emp2.txt
04/21/2020 04:53 PM 50 emp500.txt
SQL> ho type c:\datadumps\emp1.txt type c:\datadumps\emp2.txt type c:\datadumps\emp500.txt
c:\datadumps\emp1.txt
101,zahir,F
102,mohamed,R
The system cannot find the file specified.
Error occurred while processing: type.
c:\datadumps\emp2.txt
201,Hameed,A
252,Abdul,RThe system cannot find the file specified.
Error occurred while processing: type.
c:\datadumps\emp500.txt
511,Balasubramaniam,A
577,Yesudas,A
501,Janaki,A
SQL> col emp_id format a5
SQL> col emp_name format a20
SQL> col emp_type format a5
SQL> SELECT
2 emp_id,
3 emp_name,
4 emp_type
5 FROM
6 external
7 ( ( emp_id VARCHAR2(1000),
8 emp_name VARCHAR2(1000),
9 emp_type VARCHAR2(1000)
10 )
11 TYPE ORACLE_LOADER DEFAULT DIRECTORY "EX_TAB_DIR"
12 ACCESS PARAMETERS
13 ( debug = 3
14 RECORDS DELIMITED BY NEWLINE
15 CHARACTERSET we8mswin1252
16 BADFILE ex_tab_dir : 'emp_ext.bad_xt'
17 LOGFILE 'emp_ext.log_xt'
18 FIELDS TERMINATED BY "," LDRTRIM MISSING FIELD VALUES ARE NULL REJECT ROWS WITH ALL NULL FIELDS
19 )
20 LOCATION ( 'emp*.txt' ) reject limit unlimited )
21 ;
EMP_I EMP_NAME EMP_T
----- -------------------- -----
101 zahir F
102 mohamed R
201 Hameed A
252 Abdul R
511 Balasubramaniam A
577 Yesudas A
501 Janaki A
7 rows selected.
In the program listing , the external table is defined inline between the lines 7 and 20.With this method, it is easier to load the data from flat files into the database without defining the table first.
Comments Welcome.
