发表于:2007.12.28 09:26
分类: Oracle
出处：http://xsb.itpub.net/post/419/446800
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Please note consistent read and current read when UPDATE statment start.
CREATE TABLE ud2_test(c1 NUMBER,c2 NUMBER,c3 NUMBER);
INSERT INTO ud2_test VALUES (1,1,1);
COMMIT;
CREATE OR REPLACE TRIGGER trg_ud2_test
BEFORE UPDATE ON ud2_test
FOR EACH ROW
BEGIN
dbms_output.put_line(:OLD.c1 || ',' || :OLD.c2 || ',' || :OLD.c3);
dbms_output.put_line(:NEW.c1 || ',' || :NEW.c2 || ',' || :NEW.c3);
END;
session1:
update ud2_test set c1=c1+1 where c2>0;
update ud2_test set c1=c1+1 where c2>0 ;
update ud2_test set c1=c1+1 where c2>0;
session2:
set serveroutput on
update ud2_test set c1=c1+10 where c2>0;
(session1 commit)
1,1,1
11,1,1
4,1,1
14,1,1
1 row updated
rollback;
etc:
update ud2_test set c3=c3+10 where c2>0;
(session1 commit)
4,1,1
4,1,11
5,1,1
5,1,11
1 row updated
rollback;
CREATE OR REPLACE TRIGGER trg_ud2_test
BEFORE UPDATE ON ud2_test
FOR EACH ROW
BEGIN
dbms_output.put_line( :OLD.c2 || ',' || :OLD.c3);
dbms_output.put_line( :NEW.c2 || ',' || :NEW.c3);
END;
update ud2_test set c3=c3+10 where c2>0;
(session1 commit)
4,1,1
4,1,11
1 row updated
rollback;
update ud2_test set c3=c3+10 where c1>0;
(session1 commit)
4,1,1
4,1,11
4,1,1
4,1,11
1 row updated
rollback;
re: update restart