well, I don't want to start a religious thread here, but I think it is a problem that Oracle treats empty strings as nulls. an empty string is a string, allbeit a short one (just like an empty set is a set, though a small one) and thus has a datatype. a null is a marker, not a value, and has no datatype. therefore, there is (or should be) an important difference between empty strings and nulls. cheers, Lex. > > Mark W. Farnham wrote: > >> So I'm thinkin' Oracle is a high flyin' she, which partly >> explains why she thinks a zero length string is a null >> value but simultaneously understands that a numeric >> zero is not a null. > > Null is not a value. Just like infinity is not a value. Null is a > state. Or is it in this case a non-existant state? ;-) > > Which is why [NULL != NULL] as mathematical operations are not valid - > state operands are required. Infinity makes this easier to grasp e.g. > [INFINTY != INIFINTY] as the INFINITY "value" is always be greater > than the INIFINITY+1 "value". Thus it cannot ever be a value. It is a > state. Ditto for NULL. > > A string that is empty is in Oracle terms a non-existant string. E.g. > with a trailing NULL string column in a table, *nothing* is stored. > NULL simply means that there is no value for that column or variable. > > Now you can argue that there's a difference between an empty string > and a null string.. and I will simply point out that this difference > is the same as the mathematical difference between (INFINITY+1) and > INFINITY. I.e. an empty string has no value. Do not think of that > "emptiness" as a valid string value. Sheez, how can it when it does > not contain a single character? > > The way that Oracle deals with nulls has always made sense to me, > especially from an OO programming viewpoint. So I honestly do not see > what the issue is about Oracle and NULLs that seems to be an issue for > others. > > -- > Billy > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > This e-mail and its contents are subject to the Telkom SA Limited > e-mail legal notice available at > http://www.telkom.co.za/TelkomEMailLegalNotice.PDF > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > -- > //www.freelists.org/webpage/oracle-l > -- //www.freelists.org/webpage/oracle-l