On 2/3/15, 10:24 AM, "Justin Swanhart" <greenlion@gmail.com> wrote:
NULL and missing are two different concepts. Null means unknown, not missing. The data structure should have an ability to store NULL to be compatible with RDBMS semantics. While a dynamic column is similar to a NoSQL document store it is not one, and should support SQL semantics.
IMHO
--Justin
Hi Justin, My understanding has always been basically what Wikipedia says:
Null is a special marker used in Structured Query Language (SQL) to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd, SQL Null serves to fulfill the requirement that all true relational database management systems (RDBMS) support a representation of "missing information and inapplicable information".
What does Null represent if not the above? Tom