create table TEST
insert into TEST values(2,4,2).
update TESTHUA set num1=num1+2,num2=num2+8,num3=num2/num1;
select * from TEST
when oracle execute num3,the value of num1 and num2 didn't change.
when mysql execute num3,the value of num1 and num2 changed already.
num1 early than num2 because num1's position is bofore num2
It means that oracle update the field data at the same time but
the mysql not,It update the field data behind the "set" by the sequence .
2.special character: oracle: '
in mysql: null is different from '';
insert into test(ID) values(1);
insert into test(ID,name) values(2,'');
select * from test where name is null; The reuslt is only 1.
select * from test where name=''; The result is 2.
in oracle: '' is same as null;
select * from test where name is null; The reuslt is 1,2.
select * from test where name=''; No result;
来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/545828/viewspace-975780/，如需转载，请注明出处，否则将追究法律责任。