If you ever have been put in a situation where your database has a lot of objects and some of those do not have primary keys, trying to find feels like needle in the haystack. I have modified the script contributed by Mr.Tandrei and Mr.Rahul sharma. The following script gives all the tables that do not have primary keys.
For most DBAs, normalization is an understood concept, a bread and butter bit of knowledge. However, it is not at all unusual to review a database design by a development group for an OLTP (OnLine Transaction Processing) environment and find that the schema chosen is anything but properly normalized. This article by Brian Kelley will give you the core knowledge to data model.