Most portable SQL date string format

Question

Across various SQL dialects, what string representation for a Date and/or DateTime would be most likely to be interpreted correctly? Is there an SQL Standard? Are the two answers identical or similar?

EDIT:

For suggestions, can we all please comment with any known SQL dialects that don't comply?

Answer 1

I would bet the ISO 8601 date time standard would most likely be the one.

'YYYY-MM-DDThh:mm:ssTZD'

Or maybe a slight variation:

'YYYY-MM-DD hh:mm:ss'

http://www.w3.org/TR/NOTE-datetime