Oracle 读写文件 bfilename [实例]

Oracle 读写文件 bfilename [实例]
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 oneeygle 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_fileSYS                            
                                      BDUMP_DIR                      /opt/oracle/admin/conner/bdumpSYS                                                         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_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'); -- 注意这里的 User_dir 对应上面已经创建好啦的目录
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;