maria-discuss team mailing list archive

[Federico Razzoli <federico_raz@xxxxxxxx>]

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@xxxxxxxxxx> ha scritto:

 Oggetto: Re: [Maria-discuss] Restated: JSON cannot represent binary data
 A: "Justin Swanhart" <greenlion@xxxxxxxxx>
 Cc: "maria-discuss email list" <maria-discuss@xxxxxxxxxxxxxxxxxxx>
 Data: Martedì 3 febbraio 2015, 17:29
 
 On 2/3/15, 10:24 AM,
 "Justin Swanhart" <greenlion@xxxxxxxxx>
 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
 
 
 
 
 
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