Re: Preferring rows between to relational tables

[Roland Bouman]

this is builtin:

COALESCE()

coalesce returns the first not-null argument.

http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html

you might want to check out

http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html

too.

(edit: just one thing: you really cannot use:

something = NULL

or

something != NULL

if you want to check for nulls, do:

something IS NULL
or
something IS NOT NULL
or even
NOT something IS NULL

that's because NULL is not really a value, it's a marker that sais: hey, this value here is undefined. Compared to whatever ohther value, *even null itself* is never true.

)



Edited 1 time(s). Last edit at 03/16/2006 09:57AM by Roland Bouman.