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От | Daniel Schuchardt |
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Тема | Re: |
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Msg-id | 000001c38807$53c369d0$6500a8c0@DSVAIO обсуждение исходный текст |
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Список | pgsql-general |
Read the docs... Hm looking towards the doks thats the right behavoir. Also from the logical point thats the right behavoir. But I don't like it. The CAST should return an empty string in that case (looking from the practical standpoint). Hm. -----Ursprüngliche Nachricht----- Von: dev@archonet.com [mailto:dev@archonet.com] Gesendet: Mittwoch, 1. Oktober 2003 12:08 An: Daniel Schuchardt; pgsql-general@postgresql.org Betreff: Re: [GENERAL] <no subject> On Wednesday 01 October 2003 10:57, Daniel Schuchardt wrote: > Hi @ all, > > I think thats a bug: > > SELECT '#' || '#' > > will work but > > SELECT '#' || CAST(NULL AS VARCHAR) Nope - not a bug. > will return only empty rows. > My Query looks like this : SELECT field1 || field2 FROM ... If field2 > ISNULL then everything is null. CAST does not help. Broadly speaking VALUE op NULL = NULL You'll see similar issues with comparisons. You might find the article below useful: http://techdocs.postgresql.org/guides/BriefGuideToNulls -- Richard Huxton Archonet Ltd
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