Search found 124 matches

by HughDarwen
Tue Oct 11, 2011 4:25 pm
Forum: Report a Bug
Topic: MAX and MIN don't work when subtype of INTEGER defined
Replies: 2
Views: 7913

Re: MAX and MIN don't work when subtype of INTEGER defined

I can confirm that the same error doesn't arise on version 1.05 beta.

Hugh Darwen
by HughDarwen
Sat Feb 26, 2011 12:43 pm
Forum: Report a Bug
Topic: Problem with most aggregate operators
Replies: 3
Views: 6938

Re: Problem with most aggregate operators

Many thanks, Dave, and sorry for my mistake. I don't know, now, how I managed to convince myself that SUM supported expressions rather than just attribute names, but I tried exactly the same test today and it failed.

Hugh
by HughDarwen
Fri Feb 25, 2011 5:16 pm
Forum: Report a Bug
Topic: Problem with most aggregate operators
Replies: 3
Views: 6938

Problem with most aggregate operators

In the original version of Tutorial D , the syntax for most aggregate operator invocations was <agg op name> ( <rel exp>, <attribute name> ), but eventually we generalized it to allow any expression (usually an open one) in place of <attribute name>. The expression SUM(r, a + 1), where a is a numeri...
by HughDarwen
Wed Dec 08, 2010 3:54 pm
Forum: Language Issues
Topic: Subtyping gives surprising results for COUNT()
Replies: 0
Views: 19557

Subtyping gives surprising results for COUNT()

I defined type SESSION# as a subtype of INTEGER on the constraint INTEGER > 0. This type was for use as the declared type of a particular attribute in some particular base relvars. When I gave a query in DBrowser, one of whose result attributes was defined by ADD ( COUNT() AS NoOfThings ), I was a b...
by HughDarwen
Mon Nov 01, 2010 1:58 pm
Forum: Report a Bug
Topic: Rel crashes on DROP CONSTRAINT
Replies: 2
Views: 5595

Rel crashes on DROP CONSTRAINT

I've been getting a lot of crashes lately, not all of them repeatable, mostly arising from DROP statements. Here's one that does seem to be repeatable (I'll send the relevant database backup privately): Rel version 1.0.4 Beta Copyright (C) 2004 - 2010 Dave Voorhis All Rights Reserved For further inf...
by HughDarwen
Sun Oct 17, 2010 3:54 pm
Forum: Report a Bug
Topic: Backup defines virtual relvar in advance of dependent real
Replies: 1
Views: 5580

Backup defines virtual relvar in advance of dependent real

In the backup shown below the virtual relvar teacher is defined in advance of the real relvar staff, so loading it and executing it gives an error. Find "var teacher", then "var staff" to see what I mean. Hugh /*** Rel Database Backup ***/ // Created in Rel Version 1.0.4 Beta // ...
by HughDarwen
Tue Oct 12, 2010 4:31 pm
Forum: Report a Bug
Topic: Invocation of RELATION with heading/body type mismatch
Replies: 2
Views: 5064

Invocation of RELATION with heading/body type mismatch

In 1.0.4 beta:

relation { x integer, y integer } {tuple{x 1, z 1}}
is accepted and yields relation { x integer, y integer } {tuple{x 1, y 1}}.

Note the difference between the specified relation heading and that of the only tuple in the body.

Hugh (with thanks to Adrian Hudnott)
by HughDarwen
Wed Sep 29, 2010 11:53 am
Forum: Language Issues
Topic: request for INT2RAT conversion operator
Replies: 3
Views: 8089

Re: request for INT2RAT conversion operator

Oops! Sorry to have bothered you. A case of RTFM I suppose.

Chastened,
Hugh
by HughDarwen
Wed Sep 29, 2010 11:51 am
Forum: Report a Bug
Topic: Catastrophic crash after OP_EQUALS overloads
Replies: 1
Views: 4149

Catastrophic crash after OP_EQUALS overloads

I'm getting repeated crashes, not always in exactly the same place, when I test my overloads of OP_EQUALS that allow me to write, for example, PNO('P1') = 'P1'. I obtained the log appended below by running Rel 1.0.4 beta having first deleted all the files in the target Database directory. It starts ...
by HughDarwen
Tue Sep 28, 2010 11:37 am
Forum: Language Issues
Topic: request for INT2RAT conversion operator
Replies: 3
Views: 8089

request for INT2RAT conversion operator

I don't mean that the operator name has to be INT2RAT as in my subject line, but I wonder if it would be possible for such an operator to be included in, say, OperatorsMath.d (or even supplied as built-in). I ran into this requirement when I was trying to compare some real students' real exam scores...
by HughDarwen
Wed Sep 01, 2010 11:48 am
Forum: Report a Bug
Topic: Subtype without additional possrep
Replies: 4
Views: 7221

Re: Subtype without additional possrep

Sorry for a bad mistake in my bug report. It concerns this example: TYPE CIRCLE IS { ELLIPSE CONSTRAINT ( THE_A(ELLIPSE) = THE_B(ELLIPSE) ) } ; According to page 350 in Chapter 21 of our new book "Database Explorations", Rel is quite correct in rejecting this for lack of a <derived possrep...
by HughDarwen
Sun Aug 22, 2010 2:56 pm
Forum: Report a Bug
Topic: Subtype without additional possrep
Replies: 4
Views: 7221

Subtype without additional possrep

Sorry--these problems appear to have been around since before you went to beta. It's taken me a while to get around to testing S-by-C support. Having defined type ELLIPSE I tried this: TYPE CIRCLE IS { ELLIPSE CONSTRAINT ( THE_A(ELLIPSE) = THE_B(ELLIPSE) ) } ; It wasn't accepted, complaining that it...
by HughDarwen
Fri Mar 19, 2010 3:19 pm
Forum: Report a Bug
Topic: TCLOSE gives incorrect result
Replies: 1
Views: 4474

TCLOSE gives incorrect result

I tried tclose(relation{tuple{x 1, y 2}, tuple{x 2, y 3}, tuple {x 3, y 4}}) and got RELATION {x INTEGER, y INTEGER} { TUPLE {x 1, y 2}, TUPLE {x 2, y 3}, TUPLE {x 3, y 4} } I think I should have got RELATION {x INTEGER, y INTEGER} { TUPLE {x 1, y 2}, TUPLE {x 2, y 3}, TUPLE {x 2, y 3}, TUPLE {x 1, ...
by HughDarwen
Tue Feb 09, 2010 3:02 pm
Forum: Report a Bug
Topic: Script created by Backup gives run-time error
Replies: 2
Views: 6416

Script created by Backup gives run-time error

The script below was generated by pressing DBrowser's Backup button, using Version 3.18. This script represents Chris Date's supplier-and-parts database, taking advantage of Rel's UDT support for the types SNO, PNO, JNO, NAME, COLOUR, and WEIGHT. If you scroll to the end of the script you will see t...
by HughDarwen
Thu Apr 30, 2009 10:33 am
Forum: Rel Examples
Topic: Testing strings for numeric
Replies: 4
Views: 12538

Re: Testing strings for numeric

Dave, Sorry I never replied to your question about the performance of my attempted is_num operator. Maybe I'll get back to that one day but in the meantime I've been playing with IS_NUMERIC. I was worried that my definition of type SID (student identifiers consisting of the letter 'S' followed by di...