> > --- [EMAIL PROTECTED] wrote: >> There have been a few posts recently where people >> have had problems with >> nulls. Anyone got comments on the below before I >> submit it to techdocs? >> >> TIA >> >> - Richard Huxton >> >> A Brief Guide to NULLs >> ====================== >> >> What is a null? >> =============== >> A null is *not* an empty string. >> A null is *not* a value. >> A null is *not* a "special" value. >> A null is the absence of a value. >> >> >> What do nulls mean? >> =================== >> Well, they *should* mean one of two things: >> 1. There is no applicable value >> 2. There is a value but it is unknown > > Good job!, it sure helps people who don't much > background on formal database theory. > > What about adding this to the section "What does > nulls mean" > --> 3) No value has yet been assigned to that > particular attribute (field). > > > I think it would also be nice if you can add a > section on functions that deals with NULL such as > nullif() and coalesce(). These functions help users > interpret NULL values. > > > best regards, > > ludwig > > > > __________________________________________________ > Do you Yahoo!? > New DSL Internet Access from SBC & Yahoo! > http://sbc.yahoo.com > > ---------------------------(end of broadcast)--------------------------- > TIP 6: Have you searched our list archives? > > http://archives.postgresql.org > >
---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
