ORACLE PL/SQL LOB大对象

LOB

练习 1:字符大对象
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create table testclob (id number,text_col1 clob);

declare
longliteral varchar2(32767) := rpad('1', 32767, '1');
begin
execute immediate 'insert into testclob values(1,:1)' using longliteral;
commit;
end;
/

计算clob列的长度：
select DBMS_LOB.GetLength(text_col1) col1 from testclob;

--追加数据到大对象列:
DECLARE
varC CLOB;
vAStr VARCHAR2(32767);
BEGIN
-- vAStr:=',this append data';
vAStr:=rpad(',this append data:', 32767, '2');
SELECT text_col1
INTO varC
FROM testclob
WHERE id=1
FOR UPDATE;
DBMS_LOB.Append(varC,vAStr);
COMMIT;
-- DBMS_OUTPUT.put_line('append result: '|| varC);
END;
/

--DBMS_LOB.Erase(LOB数据，指定删除长度, 开始删除位置);
DECLARE
varC CLOB; --LOB data
LN NUMBER(5); --specify length
strt NUMBER(5); --start location
BEGIN
LN:=32767;
strt:=32768;
SELECT text_col1
INTO varC
FROM testclob
WHERE id=1
FOR UPDATE;
DBMS_LOB.ERASE(varC,LN,strt);
COMMIT;
DBMS_OUTPUT.put_line('擦除结果为: '|| strt);
END;
/

alter table testclob modify lob (text_col1) (shrink space); --回收的是扩展之后的extent

练习 2:二进制大对象
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conn / as sysdba
CREATE OR REPLACE DIRECTORY IMG AS '/home/oracle';
GRANT READ ON DIRECTORY IMG TO scott WITH GRANT OPTION;

conn scott/tiger
create table testblob (id number(2),pic blob default empty_blob());

CREATE OR REPLACE PROCEDURE IMG_INSERT (TID VARCHAR2,FILENAME VARCHAR2) AS
F_LOB BFILE;--文件类型
B_LOB BLOB;
BEGIN
iNSERT INTO TESTBLOB (ID, PIC)
VALUES (TID,EMPTY_BLOB ()) RETURN PIC INTO B_LOB;
--插入空的blob
F_LOB:= BFILENAME ('IMG', FILENAME);
--获取指定目录下的文件
DBMS_LOB.FILEOPEN(F_LOB, DBMS_LOB.FILE_READONLY);
--以只读的方式打开文件
DBMS_LOB.LOADFROMFILE (B_LOB, F_LOB,DBMS_LOB.GETLENGTH (F_LOB));
--传递对象
DBMS_LOB.FILECLOSE (F_LOB);
--关闭原始文件
COMMIT;
END;
/

--在/home/oracle下放一张图片1.jpg

--将该图片存入表

EXEC IMG_INSERT('1','1.png');
EXEC IMG_INSERT('2','1.txt');

练习 3:外部二进制文件
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create table testbfile(id int, fname bfile);

insert into testbfile values (1, bfilename ('IMG', '1.png'));
commit;