Re: String complements

>Why has SQL Server provided such facilities to all of its users (factors of magnitude more than the X* technologies users) but we have no such functionality?

Probably two reasons.

Firstly, SQL Server is a huge revenue earner. The reason Microsoft have invested heavily in their database technology and have allowed their XML technology to stagnate is all about money.

Secondly, the data that underpins Unicode collations is all available in XML form, and very little value is added by wrapping a functional interface around it, when you can query it directly.

Michael Kay
Saxonica

> On 15 Mar 2024, at 20:35, Dimitre Novatchev <dnovatchev@gmail.com> wrote:
> 
> > Enjoy some bedtime reading: http://www.unicode.org/reports/tr10/
> 
> Thank you, Michael, this would make an interesting read, indeed.
> 
> > We do offer a function fn:collation-key() which, given a string and a collation, 
> > returns a binary value such that the ordering of the binary values corresponds to the order of strings in the collation. 
> > This functionality is very important when delivering things like distinct-values or for-each-group using an arbitrary collation;
> > it can also be used to construct keys for maps.
> 
> Yes, I already looked at this, and this is nice compared to having no such function at all, but one must:
> 
> Know which are all the different characters (symbols) to ask for.
> 
> How to know that he has asked for all characters/symbols in the collation.
> Reconstructing this by assembling the results of a series of calls to fn:collation-key() is closer to detective or archaeologist work than of a software developer's work.
> 
> Why has SQL Server provided such facilities to all of its users (factors of magnitude more than the X* technologies users) but we have no such functionality?
> 
> Thanks,
> Dimitre 
> 
> On Fri, Mar 15, 2024 at 11:41 AM Michael Kay <mike@saxonica.com <mailto:mike@saxonica.com>> wrote:
>>> 
>>> When sorting using a collation, we must use not the codepoint for a character, but its index in the sorted characters of this collation.
>>> 
>>> This is why it is important to have a function 
>>> 
>>>     fn:collation-characters($collation-name as xs:string) as xs:string 
>>> 
>>> that returns the sorted (according to this collation) individual characters of the collation.
>>> 
>> 
>> Collations don't work character-by-character. Firstly, they split a string into "collation elements" (or collation units) which may contain several characters, and secondly, they work in a number of passes, sorting first by the primary weights of each collation unit, then the secondary weights, etc.
>> 
>> Enjoy some bedtime reading: http://www.unicode.org/reports/tr10/
>> 
>> We do offer a function fn:collation-key() which, given a string and a collation, returns a binary value such that the ordering of the binary values corresponds to the order of strings in the collation. This functionality is very important when delivering things like distinct-values or for-each-group using an arbitrary collation; it can also be used to construct keys for maps.
>> 
>> Michael Kay
>> 
> 
> 
>