Flat File Access

8/12/2019 Flat File Access

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Accessing Flat Files

• Three Different Ways

UTL_FILE

Oracle Loader

SQL Loader



What Is the UTL_FILE Package?

• Extends I/O to text files within PL/SQL

• Provides security for directories on the serverthrough the init.ora file

• Is similar to standard operating system I/O – Open files

– Get text

–

Put text – Close files

– Use the exceptions specific to the UTL_FILE

package



YesGet lines

from the

text file

Put lines

into the

text file

Morelines to

process?

No Close

the

text file

File Processing Using the

UTL_FILE Package

Open the

text file



UTL_FILE Procedures and

Functions• Function FOPEN

• Function IS_OPEN

• Procedure GET_LINE• Procedure PUT, PUT_LINE, PUTF

• Procedure NEW_LINE

•

Procedure FFLUSH• Procedure FCLOSE, FCLOSE_ALL



Exceptions Specific to the

UTL_FILE Package• INVALID_PATH

• INVALID_MODE

• INVALID_FILEHANDLE• INVALID_OPERATION

• READ_ERROR

•

WRITE_ERROR• INTERNAL_ERROR



FUNCTION FOPEN

(location IN VARCHAR2,

filename IN VARCHAR2,

open_mode IN VARCHAR2)RETURN UTL_FILE.FILE_TYPE;

FUNCTION IS_OPEN

(file_handle IN FILE_TYPE)

RETURN BOOLEAN;

The FOPEN and IS_OPEN

Functions



CREATE OR REPLACE PROCEDURE sal_status

(p_filedir IN VARCHAR2, p_filename IN VARCHAR2)

IS

v_filehandle UTL_FILE.FILE_TYPE;

CURSOR emp_info IS

SELECT last_name, salary, department_id

FROM employeesORDER BY department_id;

v_newdeptno employees.department_id%TYPE;

v_olddeptno employees.department_id%TYPE := 0;

BEGIN

v_filehandle := UTL_FILE.FOPEN (p_filedir, p_filename,'w');

UTL_FILE.PUTF (v_filehandle,'SALARY REPORT: GENERATED ON%s\n', SYSDATE);

UTL_FILE.NEW_LINE (v_filehandle);

FOR v_emp_rec IN emp_info LOOP

v_newdeptno := v_emp_rec.department_id;

...

Using UTL_FILE sal_status.sql



...IF v_newdeptno <> v_olddeptno THEN

UTL_FILE.PUTF (v_filehandle, 'DEPARTMENT: %s\n',

v_emp_rec.department_id);

END IF;

UTL_FILE.PUTF (v_filehandle,' EMPLOYEE: %s earns: %s\n',

v_emp_rec.last_name, v_emp_rec.salary);v_olddeptno := v_newdeptno;

END LOOP;

UTL_FILE.PUT_LINE (v_filehandle, '*** END OF REPORT ***');

UTL_FILE.FCLOSE (v_filehandle);

EXCEPTION

WHEN UTL_FILE.INVALID_FILEHANDLE THEN

RAISE_APPLICATION_ERROR (-20001, 'Invalid File.');

WHEN UTL_FILE.WRITE_ERROR THEN

RAISE_APPLICATION_ERROR (-20002, 'Unable to write tofile');

END sal_status;/

Using UTL_FILE sal_status.sql



External Tables

• External tables are read-only tables in which thedata is stored outside the database in flat files.

• The metadata for an external table is createdusing a CREATE TABLE statement.

• With the help of external tables, Oracle data canbe stored or unloaded as flat files.

• The data can be queried using SQL, but you cannotuse DML and no indexes can be created.



Creating an External Table• Use the external_table_clause along with the

CREATE TABLE syntax to create an external table.

• Specify ORGANIZATION as EXTERNAL to indicate that

the table is located outside the database.

•

The external_table_clause consists of theaccess driver TYPE, external_data_properties,and the REJECT LIMIT.

• The external_data_properties consist of the

following:– DEFAULT DIRECTORY

– ACCESS PARAMETERS

– LOCATION



Example of Creating an

External TableCreate a DIRECTORY object that

corresponds to the directory on the file

system where the external data sourceresides.

CREATE DIRECTORY emp_dir AS '/flat_files' ;



Example of Creating an

External TableCREATE TABLE oldemp (

empno NUMBER, empname CHAR(20), birthdate DATE)ORGANIZATION EXTERNAL(TYPE ORACLE_LOADERDEFAULT DIRECTORY emp_dir

ACCESS PARAMETERS(RECORDS DELIMITED BY NEWLINE

BADFILE 'bad_emp'LOGFILE 'log_emp'FIELDS TERMINATED BY ','(empno CHAR,empname CHAR,

birthdate CHAR date_format date mask "dd-mon-yyyy"))

LOCATION ('emp1.txt'))PARALLEL 5REJECT LIMIT 200;

Table created.



Querying External Tables

SELECT *FROM oldemp

emp1.txt



What is SQL*Loader and what is it

used for?

• SQL*Loader is a bulk loader utility used formoving data from external files into the Oracledatabase.

• SQL*Loader supports various load formats,selective loading, and multi-table loads



How does one use the SQL*Loader

utility?

• One can load data into an Oracle database byusing the sqlldr (sqlload on some platforms)utility. Invoke the utility without arguments to

get a list of available parameters. Look at thefollowing example:

• sqlldr scott/tiger control=loader.ctl



Data File

• The mydata.txt file may look like this:

• 10001,"Scott Tiger", 1000, 40

•

10002,"Frank Naude", 500, 20



Control File

load data

infile 'c:\data\mydata.csv'

into table empfields terminated by "," optionally enclosed by '"'

( empno, empname, sal, deptno )



• load data• infile *• replace• into table departments

• ( dept position (02:05) char(4),• deptname position (08:27) char(20)• )• begindata•

COSC COMPUTER SCIENCE• ENGL ENGLISH LITERATURE• MATH MATHEMATICS• POLY POLITICAL SCIENCE

Control File with in-line data

Documents

Flat File Access