- From: Bill Keese <billk@tech.beacon-it.co.jp>
- Date: Fri, 17 Oct 2003 11:40:38 +0900
- To: Michael Rys <mrys@microsoft.com>
- Cc: public-qt-comments@w3.org
Michael Rys wrote: >Just a nitpick: SQL WHERE clauses fail with a conversion error if a >conversion fails and the query processor executes a plan that leads to >the execution of the offending conversion. > >Actually, the current XQuery rules are pretty close to SQL's rules in >that respect. > > Wow, I've been away from SQL too long, I had forgotten this. I had a dim memory that SQL is also non-deterministic; you might cause/avoid hitting an exception, for example, by creating an index on a certain column. Well, if XQuery is working like SQL then at least it's something that's been proven by experience. Basically, it seems like - a (non-null) column value in a relational table (accessed via SQL) corresponds to a sequence in an XML document (accessed via XQuery) (ie, a list of values rather than just a single value) - a NULL value in a relational table (accessed via SQL) corresponds to an empty sequence. (ie, a list of no values) Other than that SQL and XQuery are "the same", so to speak. Bill
Received on Thursday, 16 October 2003 22:41:30 UTC