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²Î¼ûÎÒµÄBLOG£ºOracleϵÁУºLOB´ó¶ÔÏó´¦Àí
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1£¬ÏȲåÈëÆÕͨÊý¾Ý£¬Óöµ½´ó¶ÔÏóÁÐʹÓÃempty_blob()¹¹Ôì¿ÕµÄÖ¸Õë¡£
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/*
conn scott/tiger;
Create TableSpace ts5_21;
*/
Create Table MyLob
(
no number(8) primary key,
fname varchar2(30),
myfile blob
)
Lob (myfile) Store As
(
Tablespace ts5_21
Chunk 15K
Disable Storage In Row
);
Insert Into MyLob Values(1,'IMG_0210.JPG',empty_blob());
2£¬´´½¨Â߼Ŀ¼MYDIR
Create Directory MYDIR As 'E:\Oracle';
3£¬ÉùÃ÷Ò»¸öBLOBÀàÐͱäÁ¿£¬Ê¹ÓÃselect into Óï¾äÈÃÆäÖ¸Ïòµ½empty_blob()¹¹Ôì¿ÕµÄÖ¸ÕëËùÖ¸ÏòµÄ´æ´¢¿Õ¼ä
Select myfile Into BLOBÀàÐͱäÁ¿ from myLob Where no = 1 FOR UPDATE;
4£¬ÉùÃ÷Ò»¸öBFileÀàÐͱäÁ¿£¬¹ØÁªÂ߼Ŀ¼ºÍÎïÀíĿ¼Îļþ£¬Ê¹Óà BFileName() ½«ÆäÖ¸Ïòµ½´ý´æ´¢µÄÎļþ¡£
BFileÀàÐͱäÁ¿ := BFileName('MYDIR','IMG_0210.JPG');
5£¬Ê¹ÓÃDBMS_LOB.open()·½·¨½«BFileÀàÐͱäÁ¿ËùÖ¸ÏòµÄÎļþ´ò¿ª
DBMS_LOB.Open(BFileÀàÐͱäÁ¿);
6£¬Ê¹ÓÃDBMS_LOB.loadfromfile()·½·¨½«BFileÀàÐͱäÁ¿ËùÖ¸ÏòµÄÎļþ¶ÁÈëµ½BLOBÀàÐͱäÁ¿ËùÖ¸ÏòµÄ´æ´¢¿Õ¼ä
DBMS_LOB.LoadfromFile(BLOBÀàÐͱäÁ¿,BFileÀàÐͱäÁ¿,DBMS_LOB.getlength(BFileÀàÐͱäÁ¿));
7£¬Ê¹ÓÃDBMS_LOB.close()·½·¨½«bfileµÄ±äÁ¿ËùÖ¸ÏòµÄÎļþ¹Ø±Õ
DBMS_LOB.Close(BFileÀàÐͱäÁ¿);
8£¬Ìá½»ÊÂÎñ
Commit;
Àý×Ó;
Declare
varB blob;
varF Bfile;
Begin
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NULLÖ¸µÄÊÇ¿ÕÖµ£¬»òÕß·Ç·¨Öµ¡£
NVL (expr1, expr2)->expr1ΪNULL£¬·µ»Øexpr2£»²»ÎªNULL£¬·µ»Øexpr1¡£×¢ÒâÁ½ÕßµÄÀàÐÍÒªÒ»ÖÂ
NVL2 (expr1, expr2, expr3) ->expr1²»ÎªNULL£¬·µ»Øexpr2£»ÎªNULL£¬·µ»Øexpr3¡£expr2ºÍexpr3ÀàÐͲ»Í¬µÄ»°£¬expr3»áת»»Îªexpr2µÄÀàÐÍ
NULLIF (expr1, expr2) ->ÏàµÈ·µ»ØNULL£¬²»µÈ·µ»Øex ......
Oracle ´¥·¢Æ÷ÓÐÓï¾ä¼¶´¥·¢Æ÷ºÍÐм¶´¥·¢Æ÷
Óï¾ä¼¶´¥·¢Æ÷ µ±É¾³ý²¿ÃűíÖеIJ¿ÃźÅʱ£¬Í¬Ê±É¾³ýµôÔ±¹¤±íÖв¿ÃźÅΪ£ºold.deptnoµÄ¼Ç¼
create or replace trigger del_dept_id
after delete on dept
for each row
begin
delete from emp where deptno=:old.deptno;
end;
µ±Íù²¿Ãűí²åÈëʱ£¬Í¬Ê±ÔÚÔ±¹¤±íÖ ......
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0£ºnone
1£ºnull ¿Õ
2£ºRow-S Ðй²Ïí(RS)£º¹²Ïí±íËø£¬sub share
3£ºRow-X ÐжÀÕ¼(RX)£ºÓÃÓÚÐеÄÐ޸ģ¬sub exclusive
4£ºShare ¹²ÏíËø(S)£º×èÖ¹ÆäËûDML²Ù×÷£¬share
5£ºS/Row-X ¹²ÏíÐжÀÕ¼(SRX)£º×èÖ¹ÆäËûÊÂÎñ²Ù×÷£¬share/sub exclusive
6£ºexclusive ¶ÀÕ¼(X)£º¶ÀÁ¢·ÃÎÊʹÓã¬exclusive
......
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