Michael Widenius wrote:
Hi!
"Peter" == Peter Gulutzan <peter.gulut...@sun.com> writes:
Peter> Hi all,
Peter> On 01/15/2009 03:11 PM Peter Gulutzan wrote:
For a TIME or DATETIME or TIMESTAMP literal, one can use
'.' instead of ':' and one can skip leading fields. For example:
INSERT INTO t (datetime_column) VALUES ('1001.01.01 11.22');
For default MySQL changes the value to '1001-01-01 11:22:00'.
The MySQL Reference Manual calls this "relaxed form".
http://dev.mysql.com/doc/refman/5.1/en/using-date.html
For WL#946 "TIME/TIMESTAMP/DATETIME with fractional seconds",
'.' means something else: decimal point. The natural reading
of '11.22' is going to be '11.22 seconds' for many people.
The WL#946 HLS says "That [relaxed form] will no longer be
possible, '.' must indicate that a fraction follows."
I think we should consider these alternatives now:
1. Deprecate use of '.' as a substitute for standard
punctuation characters. The other "relaxed form" stuff
can remain. The manual should say "don't use '.' etc.".
Peter> Roy says "it is not strictly necessary".
Peter> Bernt says "I would go for 1) ...".
Peter> Konstantin says "This should be OK".
Peter> Unless more comments appear before January 31, this is the
Peter> winning option. Trudy wrote guidelines in 2006
Peter> https://inside.mysql.com/wiki/DeprecatingServerFeatures
Peter> I will try to follow them, except that instead of getting
Peter> approval from "architecture team" I will ask "ServerPT".
As Dmitri pointed out, we shouldn't deprecate '.' as substitute for
dates.
Another things is that we should stop making decisions about
incompatible changes without listening to the MySQL users. They know
more than we how MySQL is used and they are directly affected of any
incompatible change we force upon them.
2. Insist that '.' will continue to be a substitute for
standard punctuation characters if any field is missing,
but '.' will mean decimal if and only if all fields are
present and have no substitutions. Thus '11.22' means
"11 hours 22 minutes" but '00:00:11.22' means "11.22
seconds".
Peter> Roy said "option 2) will work quite well".
The question here is how PostgreSQL and ANSI does this and also what
is the logical interpretation of the number.
ISO 9075 (ANSI SQL) is very strict about this. It only allows TIME
literals with 3 or 4 digit groups, and it only allows the ':' separator
(except after the seconds part). There is no possibility for ambiguity,
as the first number is always interpreted as an hour field.
This is a literal format that is seen only by the SQL programmer, so
there is no need for extensions. Date values provided by end users need
to go through localization features, so that could be a different story.
Thanks,
Roy
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