Oracle Directory

Create directory让我们可以在Oracle数据库中灵活的对文件进行读写操作，极大的提高了Oracle的易用性和可扩展性。
其语法为:
CREATE [OR REPLACE] DIRECTORY directory AS 'pathname';

本案例具体创建如下:

            create or replace directory exp_dir as '/tmp';

目录创建以后，就可以把读写权限授予特定用户，具体语法如下:
GRANT READ[,WRITE] ON DIRECTORY directory TO username;

例如:

            grant read, write on directory exp_dir to eygle;

此时用户eygle就拥有了对该目录的读写权限。

让我们看一个简单的测试:

            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 one
            eygle test write two
            [oracle@jumper 9.2.0]$

类似的我们可以通过utl_file来读取文件:

            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.

可以查询dba_directories查看所有directory.

            SQL> select * from dba_directories;
            OWNER                          DIRECTORY_NAME                 DIRECTORY_PATH
            ------------------------------ ------------------------------ ------------------------------
            SYS                            UTL_FILE_DIR                   /opt/oracle/utl_file
            SYS                            BDUMP_DIR                      /opt/oracle/admin/conner/bdump
            SYS                            EXP_DIR                        /opt/oracle/utl_file

可以使用drop directory删除这些路径.

            SQL> drop directory exp_dir;
            Directory dropped
            SQL> select * from dba_directories;
            OWNER                          DIRECTORY_NAME                 DIRECTORY_PATH
            ------------------------------ ------------------------------ ------------------------------
            SYS                            UTL_FILE_DIR                   /opt/oracle/utl_file
            SYS                            BDUMP_DIR                      /opt/oracle/admin/conner/bdump