On 2000-02-21, Tom Lane mentioned:
> > Is there a good reason that a character literal is unknown? I'm sure the
> > reasons lie somewhere in the extensible type system, but if I wanted it to
> > be something else explicitly then I would have written DATE 'yesterday'.
>
> Remember that constants of random types like "line segment" have to
> start out as character literals
A constant of type line segment looks like this:
LSEG 'whatever'
This is an obvious extension of the standard. (Also note that this is
*not* a cast.)
The semantics of SQL throughout are that if I write something of the form
quote-characters-quote, it's a character literal. No questions asked. Now
if I pass a character literal to a datetimeish function, it's on obvious
cast. If I pass it to a geometry function, it's an obvious cast. If I pass
it to a generic function, it's a character string.
It seems that for the benefit of a small crowd -- those actually using
geometric types and being too lazy to type their literals in the above
manner -- we are creating all sorts of problems for two much larger
crowds: those trying to use their databases in an normal manner with
strings and numbers, and those trying develop for this database that never
know what type a literal is, when it should be obvious. I am definitely
for a close examination of this one.
--
Peter Eisentraut Sernanders väg 10:115
peter_e@gmx.net 75262 Uppsala
http://yi.org/peter-e/ Sweden