Обсуждение: TEXT and NULL...
Hallo all, Does it make any difference to save "no data" in a column with type TEXT or BYTEA as "" (empty string) or null? Is one of it faster or more wast of memory? Regards, Jörg Sommer -------------------------------------------------------------------------- Sommer Maschinenbau Pagenstecherstr. 146 49090 Osnabrück 0049 (0)541 125085 0049 (0)541 129557 Service@Sommer-Maschinenbau.de --------------------------------------------------------------------------
On Mon, 17 Jun 2002, Egon Sommer wrote: > Hallo all, > > Does it make any difference to save "no data" in a column with type TEXT or BYTEA as "" (empty string) or null? > Is one of it faster or more wast of memory? Always store NULL instead of empty strings. This will it make much more easier in programming where you don't have to bother about two conditions (NULL and empty string). An empty string on the other hand may be a value in an application context where NULL is per definition always the same. Storing NULL values is a good feature of DBMS so use it ;-) Querying NULL values is part of the SQL-Syntax. Best regards Herbie -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Herbert Liechti http://www.thinx.ch ThinX networked business services Adlergasse 5, CH-4500 Solothurn ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Whether storing NULL values in a relational database is a good idea is at best highly contentious. Chris Date, one of the pioneers of relational database theory, rejects them outright as a violation of the relational model. You might want to check out one of his books and then make up your own mind. One thing that an empty string has going for it is that "" = "", and nothing else does, whereas NULL is not equal to null (and is not even a value). Food for thought... Dan Weston On Mon, 17 Jun 2002, Herbert Liechti wrote: > On Mon, 17 Jun 2002, Egon Sommer wrote: > > Hallo all, > > > > Does it make any difference to save "no data" in a column with type TEXT or BYTEA as "" (empty string) or null? > > Is one of it faster or more wast of memory? > > Always store NULL instead of empty strings. This will it make much > more easier in programming where you don't have to bother about > two conditions (NULL and empty string). An empty string on the > other hand may be a value in an application context where NULL is per > definition always the same. Storing NULL values is a good feature > of DBMS so use it ;-) Querying NULL values is part of the SQL-Syntax. > > Best regards > Herbie > > >