> 本文主要介绍 Oracle下 批量导入导出图片的方法，存储过程

#### Oracle  LOB 类型介绍

##### BLOB的含义
BLOB (binary large object)，二进制大对象，是一个可以存储二进制文件的容器。 主要图片、声音文件等,保存位图

#####  CLOB的含义
CLOB(Character Large Object),它与LONG数据类型类似，只不过CLOB用于存储数据库中的大型单字节字符数据块，不支持宽度不等的字符集。可存储的最大大小为4G字节

.CLOB使用CHAR来保存数据。 如：保存XML文档。

#### 批量导入导出

##### 批量导入
``` sql
--创建表，及目录
create table image_lob(t_id varchar2(10) not null,name varchar2(30),t_image blob not null);
  
create or replace directory "images_dump" as '/home/oracle/images_dump/';

--创建存储过程
create or replace procedure img_insert(tid varchar2,vname varchar2,filename varchar2) as
f_lob bfile;
b_lob blob;
begin 
insert into image_lob(t_id,name,t_image) values(tid,vname,empty_blob()) return t_image into b_lob;
f_lob:=bfilename('images_dump',filename);
dbms_lob.fileopen(f_lob,dbms_lob.file_readonly);
dbms_lob.loadfromfile(b_lob,f_lob,dbms_lob.getlength(f_lob));
dbms_lob.fileclose(f_lob);
commit;
end;
/

--执行导入
exec img_insert(89898989,'firsouler','dbwn.png');
exec img_insert(16211779,'abc','adr.png');
```

##### 批量导出
``` sql
--创建导出目录,注意权限
create or replace directory BLOBDIR as '/home/oracle/images_exp'; 
grant read,write on directory BLOBDIR to mytest;

--创建过程,本例使用t_id,name列作为照片名字,根据t_id 排序获取rownum
CREATE OR REPLACE PROCEDURE GET_PIC_BLOB(i_xh VARCHAR2) IS
l_file UTL_FILE.FILE_TYPE;
l_buffer RAW(32767);
l_amount BINARY_INTEGER := 32767;
l_pos INTEGER := 1;
l_name VARCHAR2(30);
l_id VARCHAR2(30);
l_blob BLOB;
l_blob_len INTEGER;
BEGIN
with tmp_image as (select rownum as rn,t_id,name,t_image from image_lob order by t_id) 
select t_id,name,t_image into l_id,l_name,l_blob  from tmp_image where rn = i_xh;
l_blob_len := DBMS_LOB.GETLENGTH(l_blob);
l_file := UTL_FILE.FOPEN('BLOBDIR', l_id || '_' || l_name || '.jpg', 'WB', 32767);
WHILE l_pos < l_blob_len LOOP
DBMS_LOB.READ(l_blob, l_amount, l_pos, l_buffer);
UTL_FILE.PUT_RAW(l_file, l_buffer, TRUE);
l_pos := l_pos + l_amount;
END LOOP;
UTL_FILE.FCLOSE(l_file);
EXCEPTION
WHEN OTHERS THEN
dbms_output.put_line(SQLERRM); 
IF UTL_FILE.IS_OPEN(l_file) THEN
UTL_FILE.FCLOSE(l_file);
END IF;
RAISE;
END GET_PIC_BLOB;
/

--循环导出200个图片,以列t_id排序获取rownum
declare
cursor cur is
with  t as (select rownum as rn from image_lob order by t_id) select rn from t  where rownum <= 200; --导出前200张
begin
for rec in cur loop
GET_PIC_BLOB(rec.rn);
end loop;
end;
/
```

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