Re: unload and null values

Carpenter, Matthew wrote: > > I tried this also. > unload to test.unl select col1, "" from table> > I received this: > > 1|| > 2|| > 3|| > 4|| > 5|| > > Just to make sure I had a null in the second column I created a > table that would not accept nulls in the second column. I tried > to load the new .unl file into the test table. I received > an error that said unable to insert null into column. > > On-Line 7 A while ago, I asked the trivia question: When does SE return a VARCHAR value? The answer is that in 7.x SE, when you SELECT "", it is treated as a zero-length VARCHAR string. Further, a zero-length VARCHAR string is distinct from a NULL VARCHAR; the first has an on-disk representation of a single zero byte, but the second has a 2-byte representation with values 0x01 0x00 (length one, value zero). However, it is not possible to distinguish between the two plain text (UNLOAD format) representations - which is irritating but so. In earlier versions, SELECT "" was equivalent to a CHAR(1) with a value of ' ', I believe. -- Jonathan Leffler (jleffler@informix.com, jleffler@earthlink.net) Guardian of DBD::Informix v0.60 -- see http://www.perl.com/CPAN #include <disclaimer.h>