strange constraint behavior
Date: Mon, 10 Oct 2016 16:48:14 +0300
Message-Id: <4812A130-901F-429D-AA1D-4CDB9DB20CB4_at_gmail.com>
hello, look at new patch from developer and found strange construction, here I’ll try to reproduce what they want to do:
create table tt as select level id from dual connect by level <=100; alter table tt add flag varchar2(50) default '' not null ; Table altered.
select dump (flag,8 ) as dmp from tt ;
DMP
NULL
NULL
…..
NULL select count (*) from tt where flag is null;
COUNT(*)
0
select count (*) from tt where flag is not null;
COUNT(*)
100
How it is possible ? =)))
ps: if I add default null, then all goes well:
alter table tt add flag varchar2(50) default null not null ; alter table tt add flag varchar2(50) default null not null
*
ERROR at line 1:
ORA-01758: table must be empty to add mandatory (NOT NULL) column
create table tt as select level id from dual connect by level <=100; alter table tt add flag varchar2(50) default null not null ; alter table tt add flag varchar2(50) default null not null
*
ERROR at line 1:
ORA-01758: table must be empty to add mandatory (NOT NULL) column
ps: sorry for my English
-- http://www.freelists.org/webpage/oracle-lReceived on Mon Oct 10 2016 - 15:48:14 CEST