Oracle read/write file bfilename [instance]

Oracle read/write file bfilename [instance]
Create directory allows us to flexibly read and write files in Oracle databases, greatly improving the ease of use and scalability of Oracle.
Its syntax is:
CREATE [or replace] DIRECTORY directory AS 'pathname ';

This case is created as follows:
Create or replace directory exp_dir as '/tmp ';
 

After the directory is created, you can grant the read and write permissions to specific users. The specific syntax is as follows:
Grant read [, WRITE] on directory directory TO username;

For example:
Grant read, write on directory exp_dir to eygle;
 

In this case, the user eygle has the permission to read and write the directory.

Let's look at a simple test:
SQL> create or replace directory UTL_FILE_DIR as '/opt/oracle/utl_file'; Directory created.
SQL> declare
2 fhandle utl_file.file_type;
3 begin
4 fhandle: = utl_file.fopen ('utl _ FILE_DIR ', 'example.txt', 'w ');
5 utl_file.put_line (fhandle, 'eygle test write one ');
6 utl_file.put_line (fhandle, 'eygle test write two ');
7 utl_file.fclose (fhandle );
8 end;
9/
PL/SQL procedure successfully completed.
SQL>!
[Oracle @ jumper 9.2.0] $ more/opt/oracle/utl_file/example.txt eygle test write oneeygle test write two [oracle @ jumper 9.2.0] $
 

Similarly, you can use utl_file to read files:
SQL> declare
2 fhandle utl_file.file_type;
3 fp_buffer varchar2 (4000 );
4 begin
5 fhandle: = utl_file.fopen ('utl_file_dir', 'example.txt ', 'R ');
6
7 utl_file.get_line (fhandle, fp_buffer );
8 dbms_output.put_line (fp_buffer );
9 utl_file.get_line (fhandle, fp_buffer );
10 dbms_output.put_line (fp_buffer );
11 utl_file.fclose (fhandle );
12 end;
13/
Eygle test write one
Eygle test write two
PL/SQL procedure successfully completed.
 

You can query dba_directories to view all directories.
SQL> select * from dba_directories;
OWNER DIRECTORY_NAME DIRECTORY_PATH
------------------------------------------------------------------------------------------
SYS UTL_FILE_DIR/opt/oracle/utl_fileSYS
BDUMP_DIR/opt/oracle/admin/conner/bdumpSYS EXP_DIR/opt/oracle/utl_file
 

You can use drop directory to delete these paths.
SQL> drop directory exp_dir;
Directory dropped
SQL> select * from dba_directories;
OWNER DIRECTORY_NAME DIRECTORY_PATH
------------------------------------------------------------------------------------------
SYS UTL_FILE_DIR/opt/oracle/utl_fileSYS
BDUMP_DIR/opt/oracle/admin/conner/bdump
 

Create or replace directory USER_DIR as 'E: \ PLSQL \ 310 \';

DECLARE
V_content VARCHAR2 (1800 );
V_bfile BFILE;
Amount INT;
Offset INT: = 1;

BEGIN
V_bfile: = bfilename ('user _ dir', 'test. TXT '); -- note that the User_dir corresponds to the directory already created above.
Amount: = DBMS_LOB.getlength (v_bfile );
DBMS_LOB.OPEN (v_bfile );
DBMS_LOB.READ (v_bfile, amount, offset, v_content );
DBMS_LOB.close (v_bfile );
DBMS_OUTPUT.PUT_LINE (v_content );
END;