Wikipedia's explanation sounds like a way to say nothing, while still pretending they are saying something. An information does not exist "in the database"? This is obvious for anyone! I don't know a single person stupid enough to think that NULL is a valid name or telephone number :) The open question is: is the datum *unknown* or *missing* "in the reality"? Or, if you prefer: does it mean that I don't know your telephone number, or does it mean that you don't have a telephone? I totally agree with Justin's view. Any other interpratation does not justify the special threatment of NULL pseudo-values in SQL. Regards Federico -------------------------------------------- Mar 3/2/15, Tom Worster <fsb@thefsb.org> ha scritto: Oggetto: Re: [Maria-discuss] Restated: JSON cannot represent binary data A: "Justin Swanhart" <greenlion@gmail.com> Cc: "maria-discuss email list" <maria-discuss@lists.launchpad.net> Data: Martedì 3 febbraio 2015, 17:29 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 _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp