I was discussing with few of my friends on the topic 'Codds rule'. I heard them say that 'SQL Server' and 'Oracle' supports all of the 12 codd's rule but DB2 doesn't support few of them!! I was surprised and then later got confused myself :)
Actually to my knowledge there is no RDBMS product (be it, Microsoft SQL Server or Oracle or DB2) which satisfies all of the 12 rules of CODD.
Hopefully in few days i will write about my knowledge on this subject and leave it open for others comments :)