On Thu, Sep 11, 2008 at 12:19:44PM +0200, Gilles Ganault scratched on the wall:
> So I guess a NULL is different from a column that was never set to > anything when creating the record? There is no such thing as "a column that was never set to anything." You might not explicitly set a value, but something is always recorded into the record. > Here's an example: > ====== > //Leave col2 empty instead of NULL > $sql = "INSERT INTO mytable (id,col1) VALUES (NULL,?)"; > $insert = $dbh->prepare($sql); > $insert->execute(array($argv[1])); > ====== In this case, "id" will have a NULL assignment (even if it has a non-NULL default value) and "col2" will be assigned its default value. All columns have a default value. You can associate an explicit default value to a column when you create the table. Otherwise, the default value is assumed to be NULL. A NULL assignment is SQL's way of representing an undefined/unknown value. This is a bit different than the way many popular scripting languages use an "undef" value or the way that C/C++ uses NULL. -j -- Jay A. Kreibich < J A Y @ K R E I B I.C H > "'People who live in bamboo houses should not throw pandas.' Jesus said that." - "The Ninja", www.AskANinja.com, "Special Delivery 10: Pop!Tech 2006" _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
